Traditional Birthstone Calendar Month Genuine Cabochon Stone Genuine Faceted Stone January Garnet Garnet February Amethyst Amethyst March Bloodstone Aquamarine April Pearl or Mother-of-Pearl Diamond May Green Onyx Emerald June Moonstone Alexandrite or Pearl July Jasper Ruby August Carnelian Peridot September Lapis Lazuli Blue Sapphire October Opal Tourmaline (pink) November Citrine Citrine or Topaz (golden) December Turquoise Zircon or Tourmaline (blue) Gemstones of the Zodiac Sign Dates Stone Aquarius January 21–February 21 Garnet Pisces February 22–March 21 Amethyst Aries March 22–April 20 Bloodstone Taurus April 21–May 21 Sapphire Gemini May 22–June 21 Agate Cancer June 22–July 22 Emerald Leo July 23–August 22 Onyx Virgo August 23–September 22 Carnelian Libra September 23–October 23 Peridot Scorpio October 24–November 21 Beryl Sagittarius November 22–December 21 Topaz Capricorn December 22–January 20 Ruby Stone List Amethyst General
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Traditional Birthstone Calendar
Month Genuine Cabochon Stone Genuine Faceted Stone January Garnet Garnet February Amethyst Amethyst March Bloodstone Aquamarine April Pearl or Mother-of-Pearl Diamond May Green Onyx Emerald June Moonstone Alexandrite or Pearl July Jasper Ruby August Carnelian Peridot September Lapis Lazuli Blue Sapphire October Opal Tourmaline (pink) November Citrine Citrine or Topaz (golden) December Turquoise Zircon or Tourmaline (blue)Gemstones of the Zodiac Sign Dates Stone Aquarius January 21–February 21 Garnet Pisces February 22–March 21 Amethyst Aries March 22–April 20 Bloodstone Taurus April 21–May 21 Sapphire Gemini May 22–June 21 Agate Cancer June 22–July 22 Emerald Leo July 23–August 22 Onyx Virgo August 23–September 22 Carnelian Libra September 23–October 23 Peridot Scorpio October 24–November 21 Beryl Sagittarius November 22–December 21 Topaz Capricorn December 22–January 20 Ruby
Stone List Amethyst
General
Category Mineral variety
Chemical formula
Silica (silicon dioxide, SiO2)
Identification
Color Purple, violet
Crystal habit 6-sided prism ending in 6-sided pyramid (typical)
Crystal system rhombohedral class 32 Specific gravity 2.65 constant; variable in impure varieties
Twinning Dauphine law, Brazil law, and Japan law
Optical properties Uniaxial (+)
Cleavage None Refractive index nω = 1.543–1.553 nε = 1.552–1.554
The deep colors are the most valuable, particularly a rich purple with rose flashes. The "Siberian" deep purple with red and blue flash commands the highest prices. So-called green amethyst does not really count as amethyst, which is by definition violet or purple. Lighting In artificial light amethyst does not display its best color. It looks best in daylight, more precisely, particularly just after sunrise and before sunset, when the light is soft and warm. Clarity A fine amethyst is transparent, which means, the light passes through the stone unhindered. A translucent amethyst slightly weakens the passage of the light through the stone. The best quality amethyst is "clean", free of visible inclusions of any kind. As the amethyst is plentiful, there is little reason to buy stones with visible inclusions. Cut Due to the variability of the color distribution in the crystals, amethyst is often cut as brilliant round to maximize the color. Other cuts can be used when the color is better distributed. Amethyst is available in a wide range of calibrated sizes and shapes, including many fancy shapes.Amethyst location and deposits The most important deposits are in Brazil, namely the "Palmeira" amethysts of Rio Grande do Sul and the "Maraba" amethysts of Para. Other deposits are found in Bolivia, Canada, India, Madagascar, Mexico, Myanmar (Burma), Namibia, Russia, Sri Lanka, United States (Arizona), Uruguay and Zambia Common Amethyst treatments Heat treatment of 878-1382 degrees F (470-750 degrees C) results in light yellow, red-brown, green or colorless varieties Amethyst is the birthstone for those who are born in February or for the Zodiacsign of Pisces.Alexandrite A type of crysoberyl
The mineral or gemstone chrysoberyl, not to be confused with beryl, is an aluminate ofberyllium with the formula BeAl2O4.[1] The name chrysoberyl is derived from the Greek words χρυσός chrysos and βήρυλλος beryllos, meaning "a gold-white spar". Despite the similarity of their names, chrysoberyl and beryl are two completely different gemstones. Chrysoberyl is the third-hardest frequently encountered natural gemstone and lies at 8.5 on the hardness scale, between corundum (9) and topaz (8).[2]
An interesting feature of its crystals are the cyclic twins called trillings. These twinned crystals have a hexagonal appearance, but are the result of a triplet of twins with each "twin" oriented at 120o to its neighbors and taking up 120o of the cyclic trilling. If only two of the three possible twin orientations are present, a "V"-shaped twin results.
Alexandrite is one of the rarest of all colored gemstones and is famed for its color change from green in daylight to red under incandescent light. Fine faceted alexandrite over 1 carat is more valuable than sapphire, ruby oremerald.Alexandrite is a strongly pleochroicgem that will exhibit emerald green, red and orange-yellow colors and tend to change color in artificial light compared to daylight. The color change from red to green is due to strong absorption of light in the yellow and blue portions of the spectrum. Typically,alexandrite has an emerald-green color in daylight but exhibits a raspberry-red color in incandescent light.According to a popular but probably apocryphal story, alexandrite was discovered by the Finnish mineralogist Nils Gustaf Nordenskjold, (1792 -1866) on the tsarevitch Alexander's sixteenth birthday on April 17, 1834 and named alexandrite in honor of the future Tsar Alexander II of Russia. It is apparently true that alexandrite was first identified (but not discovered) by Nordenskjold, but likely some years earlier, around 1831. It was Count Lev Alekseevich Perovskii (1792-1856) who named the gem alexandrite.
Alexandrite is very rare because of its chemical composition. While it is a form of chrysoberyl, it has an extra trace elemement in addition to iron and titatnium. It is the presence of chromium that gives it the emerald-green hue in daylight. Alexandrite exhbiting chatoyancy or the cat's eye effect is known, but very rare.The original source of alexandrite in the Ural mountains in Russia has been worked out. An important alexandrite deposit was found in 1987 in Minas Gerais in Brazil, and other deposits are found in Burma, Madagascar, Sri Lanka, India(Andra Pradesh) and Tanzania.Alexandrite is rarely found in larger sizes. The largest cut alexandrite weighs 66 carats and is in the Smithsonian Institution in Washington, D.C.
Almandite garnet
Category Silicate mineral
Chemical formula Fe2+3Al2Si3O12
Identification
Color reddish orange to red, slightly purplish red to reddish purple and usually dark in tone
Optical properties Single refractive, and often anomalous double refractive [1]
Refractive index 1.790 (+/- .030) [1]
Birefringence none
Pleochroism none
Dispersion .024 [1]
Ultravioletfluorescence inert
Absorption spectra usually at 504, 520, and 573nm, may also have faint lines at 423, 460, 610 and 680-690nm [1]
IntroductionAlmandine Garnet, or almandite garnet belongs to the large and varied mineral group of garnet. Garnet comes from the Latin word "granatus", which means grain, because many garnet deposits are small grains of red crystals in or on their host rock. The dark brownish or purplish red stone is popular for its excellent hardness (7.5 on the Mohs scale) and its brilliance due to its high refractive index. Garnet is the January birthstone.
Almandine Garnet colors The color is a pure, dark brownish or purplish red. Its deep red color is due to the presence of iron.Buying Almandine Garnet Color Pure, deep red is the most desirable color. LightingClarity In general, almandine garnet is an eye clean gem. Almandine garnet sometimes has asbestos fiber inclusions. These will produce four-ray, rarely six-ray, star stones when properly cut. They are highly prized by collectors because of their rarity. Cut Very large crystals exist, but because of their dark tone, only small to medium sized gems are faceted. These are often cut slightly shallow, to let light pass through. Star stones are cut en cabochon. Almadine garnet is found in a full range of shapes, including round, oval, pear and trillion.Almandine Garnet location and deposits Almandine Garnets are found in Brazil, India, Madagascar, Sri Lanka and the United States. Smaller deposits exist in Austria and the Czech Republic. Almandine garnet star-stones are found in India and the United States (Idaho).Common Almandine Garnet treatments Like most garnet the Almandine Garnet is not artificially enhanced in any way Amazonite troduction
Amazonite is a gemstone variety of green microcline, a feldspar mineral. It is named after the Amazon river in Brazil. Surprisingly, no deposits of it have been found there. The name may refer to the variable green shades of the rainforest along the big river that are reflected in the gemstone. Amazonite, is usually cut encabochon, with a rounded and convex polished surface. In fact a fine quality amazonite can be mistaken for precious jade. Like jade, Amazonite is often carvedas well. Amazonite
does not undergo any kind of treatment. Its relative softness of 6-6.5 on the Mohs scale makes Amazonite vulnerable to pressure and scratches and requires some care. Amazonite, though not common, is still very affordable.Amazonite is said to calm one's emotions and soothe nerves, and to enhance creativity and the ability to express oneself. Perhaps the strongest recommendation of its metaphysical powers is that Amazonite is said to make your married life happier.
Amazonite colors Amazonite color varies from green, yellow-green to blue-green. The color distribution is irregular. Some gemstones may also exhibit fine white streaks.Buying Amazonite Amazonite is slightly soft, 6-6.5 on the (Mohs scale), sensitive to pressure and be scratched by harder stones. It is advisable to store amazonite stones in separate boxes.Color Amazonite of a saturated, evenly distributed green would be the best choice when it comes to color.Lighting Amazonite exposes its beauty best in daylight, more precisely in the hours after sunrise and before sunset, when the light is warm and soft.Clarity Amazonite is opaque to translucent and rarely transparent. Its luster is vitreous.Cut Amazonite is usually cut en cabochon. The green stone, set in silver, creates nice pieces of jewelry, be it bracelets, necklaces, rings, earrings, or brooches and pendants. Ornamental objects can be carved as well.Amazonite location and deposits The most important deposits are found in Colorado (since 1876). Other locations are in Brazil, India, Kenya, Madagascar, Namibia, Russia and Zimbabwe.Common Amazonite treatments Amazonite is not enhanced.Amazonite gemology Species: Feldspar Color: Green, blue-green Chemical composition: KalSi3O8 potassium aluminum silicate Crystal system: Triclinic, prismatic Hardness: 6-6.5 (Mohs scale) Specific gravity: 2.56 – 2.58
Refractive index: 1.522 – 1.530 Birefringence: -0.008 Color of streak: White, Absorption spectrum: Not diagnostic Fluorescence: Weak; olive-greenThe Amazonite zodiacThe best recommendation of its metaphysical power states: Amazonite makes your married life happier.The safest approach is to wear the gemstone in skin contact to the troubled part of the body. Amazonite is said to calm one's emotions and soothe nerves, and to enhance creativity and the ability to express oneself. The deeper the color of the amazonite, the more intense the effect is said to be.
Ametrine Ametrine Sometimes amethyst and citrine colors are found in the same crystal ofquartz. These bicolor yellow and purple quartz gemstones are called ametrine.Ametrine is a very durable gemstone suited for a variety of jewelry uses. Ametrine is most typically faceted in a rectangular shape with a 50/50 pairing of amethystand citrine, though more creative cuts are becoming popular. Ametrine deposits are limited.Ametrine colors Ametrine comes in bands of yellow and purple. The colors only reach a medium level of saturation and are never very vivid (except in synthetic ametrine). Ametrine typically exhibits an abrupt color transition.Color The two colors don't offer choices, cut is all that counts. Lighting It looks best in daylight, more precisely, particularly just after sunrise and before sunset, when the light is soft and warm. Clarity Ametrine, like most quartz, is typically quite clean with good luster.
Ametrine location and deposits The Anahi Mine in Bolivia is the major world producer of ametrine. Other deposits are found in Brazil (Rio Grande de Sul). Ametrine gemology Species: Quartz
Color: Bands of yellow and purple Chemical composition: SiO2 silicon dioxide Crystal system: (Trigonal) compact Hardness: 7 (Mohs scale) Specific gravity: 2.65 Refractive index: 1.54 - 1.55 Birefringence: +0.009 Color of streak: White Absorption spectrum: Cannot be evaluated Fluorescence: NoneThe Ametrine zodiac, myth & legend Ametrine combines the powers of amethyst and citrine in one gem. Therefore ametrine can be the birthstone for those who are born in February or for theZodiac sign of Pisces.Ametrine can be assigned to the planets Jupiter, Mercury, Neptune and Pluto. Ametrine could be said to be of help for headaches, pancreas and backache. Andalusite
Category Silicate mineral nesosilicate
Chemical formula Al2SiO5
Crystal symmetry 2/m 2/m 2/m - Dipyramidal
Unit cell a = 7.7980 Å b = 7.9031 Å c = 5.5566 Å; Z = 4
Identification
Color Pink, violet, yellow, green, white, gray; in thin section, colorless to pink
Andalusite is named after Andalusia, the province of Spain where it was first discovered. Andalusite is a strongly pleiochroic gem that shows different colors when viewed from different directions. While it is a strikingly beautiful gem, it is largely unknown by the gem buying public. With a hardness of 7.5 on the Mohs scale, it is very suitable for all kinds of jewelry.Andalusite location and deposits Deposits are found in Australia, Brazil, Canada, Russia, Spain (Andalusia), Sri Lanka and the United States. Apatite
Category Phosphate mineral group
Chemical formula
Ca5(PO4)3(F,Cl,OH)
Identification
Color Transparent to translucent, usually green, less often colorless, yellow, blue to violet, pink, brown.[1]
Apatite is infrequently used as a gemstone. Transparent stones of clean color have been faceted, and chatoyant specimens have been cabochon cut.[1]
Chatoyant stones are known ascat's-eye apatite,[1] transparent green stones are known as asparagus stone,[1] and blue stones have been called moroxite.[4]
Crystals of rutile may have grown in the crystal of apatite so when in the right light, the cut stone displays a cat's eye effect. Major sources for gem apatite are[1] Brazil, Burma, and Mexico. Other sources include[1]
Canada, Czechoslovakia,Germany, India, Madagascar, Mozambique, Norway, South Africa, Spain, Sri Lanka, and theUS. It is also used in other countries.Apatite colors The range of colors includes colorless, pink, yellow, green, blue and violet. Color A rare variety is a rich purple from Maine. Blue Brazilian stones are second in demand. A light green variety of apatite carries the trade name "asparagus stone". The recent availability of the neon blue-green variety from Madagascar has resulted in more apatite jewelry. The color of the best specimens of this type rivals the famed Paraiba tourmalines, but apatite lacks tourmaline's toughness andhardness. As for any other gems, color saturation defines the value.Clarity Apatite is a transparent gemstone. Some of the blue and yellow apatite showchatoyancy and can be cut as cat's eyes. Apatite location and deposits Apatites are found in Brazil, India, Kenya, Madagascar, Mexico, Myanmar (Burma), Norway, Sri Lanka, South Africa and the United States. Aquamarine
Refractive index nω = 1.564–1.595, nε = 1.568–1.602
Birefringence δ = 0.0040–0.0070
Ultravioletfluorescence None (some fracture filling materials used to improve emerald's clarity do fluoresce, but the stone itself does not)
The name derives from the Latin expression for seawater.Aquamarine is a member of the beryl family and is known for its delicate blue or blue green coloring, which accounts for its name. Aquamarine is the birthstone for March. Aquamarine is a popular stone with very good hardness and luster.
Aquamarine colors Like seawater, aquamarine comes in blue and green blue color. The more saturated the color, the higher the value, though almost all aquamarine has a light tone.
Color Aquamarine is colored by trace amounts of iron that find their way into the crystal structure. A saturated blue is the most desired color.
Clarity Aquamarines of the best quality are clear, transparent gems. Some gems can carry inclusions of long, hollow rods, a trademark of the beryl family. Aligned traces of foreign minerals, a rare feature, cause a cat's eye effect or star effect (asterism) with six rays in a vivid sheen. Cat's eye aquamarine and star aquamarine usually command premium prices. Aquamarine location and deposits The leading producer of aquamarine is Brazil, with many mines spread
throughout the country. Other deposits found in Australia, Myanmar (Burma), China, India, Kenya, Madagascar, Mozambique, Namibia, Nigeria, Pakistan, Zambia, Zimbabwe, as well as in several U.S. locations.
Common Aquamarine treatments Most aquamarines have been heat treated to produce the popular blue-green colors from less desirable yellow or pale stones. Lower quality stones are heated to 725-850 degrees F (400-450 degrees C) in order to change the color in favor of the desired, permanent aquamarine blue. Higher temperatures would result in discoloration.
Aquamarine is the birthstone for those born in March. Aquamarine is said to be of help for arthritis, eye inflammation, sore throat and varicose veins
Aventurine
Most gemstone names are unambiguous, but Aventurine is an exception. The name is used both foraventurine feldspar and aventurine quartz. The aventurine feldspar is now commonly sold under the namesunstone, leaving the name aventurine to be used mainly for the quartz variety.The reason both these gems were labelled as aventurine is due to their resemblance to a type of Italian glass known as aventurine or goldstone.
The majority of green and blue-green aventurine originates in India (particularly in the vicinity of Mysore and Madras) where it is employed by prolific artisans. Creamy white, gray and orange material is found in Chile, Spain and Russia. Most material is carved into beads and figurines with only the finer examples fashioned into cabochons, later being set into jewellery.
Beryl, not well known to the general public, is one of the most important gem minerals. Beryl is colorless in pure form. The many different impurities give beryl its varied coloration. Without these splendid color varieties, beryl would be a rather ordinary gemstone with only average fire and brilliance. Emerald is the green andaquamarine is the blue variety of beryl. The name beryl is used for the red and golden varieties. Goshenite, Morganite, Red beryl, Golden beryl and heliodor
Beryl of various colors is found most commonly in granitic pegmatites, but also occurs in micaschists in the Ural Mountains, and limestone in Colombia. Beryl is often associated with tinand tungsten ore bodies. Beryl is found in Europe in Norway, Austria, Germany, Sweden(especially morganite), and Ireland, as well as Brazil, Colombia, Madagascar, Russia, India, South Africa, the United States, and Zambia. U.S. beryl locations are in California, Colorado,Connecticut, Idaho, Maine, New Hampshire, North Carolina, South Dakota and Utah.
Carnelian is a brownish red to red-orange variety of chalcedony or cryptocrystallinequartz. Its name is believed to come from a variety of cherry known as kornel.
It also is one of the birthstones listed in the ancient Arabic, Hebrew and and Roman tables and is a Zodiac birthstone for the sign of Virgo.
The most important carnelian deposits are found in Brazil, Uruguay, India and Madagascar.
Chalcedony Technically, chalcedony is any form of microcrystalline or cryptocrystalline quartz, meaning any form of quartz whose crystals are too small to be seen without high magnification. In common practice, only the translucent, single color types are sold as "chalcedony", whereas the rest of this group is sold under individual variety names, such as agate, carnelian, bloodstone, jasper or onyx. Chalcedony is named after the ancient seaport of Chalcedon (Kardikoy, Turkey).
Gemstone quality diopside is found in two forms: the black star diopside and the chrome diopside (which includes chromium giving it a rich green colour). At 5.5–6.5 on the Mohs scale, chrome diopside is relatively soft to scratch. Mohs scale of hardness does not measure tensile strength or resistance to fracture.
Violane is a manganese rich variety of diopside, violet to light blue in colour.[7]
Diopside location and deposits Diopside deposits are found in Austria, Finland, India, Madagascar, Myanmar, South Africa, Sri Lanka and the United States. Chrome diopside has thus far been found only in Russia. Violane is only found in Piedmont, Italy. Chrysocolla
The name comes from the Greek chrysos, "gold", and kolla, "glue", in allusion to the name of the material used to solder gold, and was first used by Theophrastus in 315 BCE.Chrysocolla is one of the lesser known gemstones, but it is a fascinating mineral. It is sometimes confused with turquoise due to its color and its greasy vitreous luster.Chrysocolla is one of a small group of copper-bearing gems that includes malachite, azurite, larimar, oregon sunstone and paraiba tourmaline, as well as turquoise.By composition, chrysocolla is a hydrous copper silicate, often with traces of oxides of copper, iron and manganese. It is a fairly soft stone at 2-4 on the Mohs scale, somewhat softer than turquoise. It is almost always opaque, and often occurs in shades of blue and green that have similarities to turquoise.Traditionally chrysocolla is said to alleviate fear, guilt, and nervous tension. It is thought to crystallize feelings of spiritually centered love, acceptance and tolerance toward others.Chrysocolla deposits are found in Chile, Israel, Mexico, Peru, Russia, Nevada in the USA and in the Congo in Africa.
Chrysoprase
Chrysoprase is considered the rarest and most valuable stone in the chalcedony quartz group. That's quite a distinction considering that the chalcedony species includes agate,chalcedony, onyx, carnelian, bloodstone andjasper. But chrysoprase, it is fair to say, is also the least known of all the chalcedony varieties.The term chalcedony refers both to the bluish-white-gray variety in particular and to all the cryptocrystalline quartzes in general. The cryptocrystalline quartzes have microscopically small crystals and a waxy or dull luster in their natural state. The familiar macrocrystalline quartzes such as amethystand citrine have much larger crystals which are recognizable with the naked eye, and have a vitreous luster.The name chrysoprase comes from the Greek for "gold-leek", though the name seems misapplied today since chrysoprase is typically an apple-green to deep green. Chrysoprase is colored by traces of nickel and is in fact one of the few gemstones colored by nickel. Most green gemstones are colored by iron (such asperidot), chromium (emerald, chrome tourmaline, chrome diopside) or vanadium (tsavorite garnet).The color of chrysoprase can be quite vivid and is reminiscent of fine jade. The gemological references warn that the color can fade under prolonged exposure to sunlight or when heated, though the color may recover under moist storage.Chrysoprase has a hardness of 6.5 to 7 on the Mohs scale, and a density
of 2.58-2.64. It has a refractive index of 1.530-1.540. It ranges from translucent to opaque.Chrysoprase has been used as a decorative stone since ancient times. A favorite of Frederick the Great of Prussia, chrysoprase can be seen decorating many buildings in Prague, including the Chapel of St Wenceslas. Today chrysoprase is carved or fashioned incabochons or beads. It is also popular for intaglios and cameos.Like all forms of chalcedony, chrysoprase is durable enough for all kinds of jewelry applications, including rings. Chrysoprase is not known to be treated in any way, though dyed green agate is sometimes used as a simulant.Chrysoprase occurs in serpentine rocks and in weathered materials of nickel ore deposits. The most famous historical deposits were in Poland, but that mine has been worked out since the 14th century. Current sources include Australia, Brazil, India, Madagascar, Tanzania,Kazakhstan, Russia, Zimbabwe, South Africa, Tanzania and the USA (California).
Citrine is one of the most popular and affordable gemstones. Named after the French word for lemon, "citron", most citrines are actually more of a golden than lemon yellow. Citrine colors includes yellow to gold to orange brown and red shades of transparent quartz. In ancient times, citrine was carried as a protection against snake venom and evil thoughts. Today citrine is known as the merchant's stone and is associated with success and prosperity. Natural citrines are mostly pale yellow to golden. Much of the citrine in the market is heat-treated amethyst, which nearly always has a reddish tint.Citrine location and deposits The most important deposits of natural citrine are in Brazil. Other locations include Argentina, Madagascar, Myanmar (Burma), Namibia Russia, Scotland and Spain.Common Citrine treatments Natural citrine is untreated and will typically exhibit some color zoning. Many of the citrine in the market have been produced by heat-treating amethyst. The
heat-treated stones will usually exhibit a reddish tint.Citrine gemology Species: Quartz Color: Light to dark yellow, gold-brown Chemical composition: SiO, silicon dioxide Crystal system: Hexagonal (trigonal), hexagonal prisms with pyramids Hardness: 7 (Mohs scale) Specific gravity: 2.65 Refractive index: 1.544 - 1.553 Birefringence: +0.009 Optical character: Color of streak: White Absorption spectrum: Not diagnostic Fluorescence: NoneThe Citrine zodiac, myth & legend Citrine is often used as a birthstone of November along with topaz.In Antiquity, as well as in the Middle Ages people believed that the cosmos is reflected in gemstones. Citrine is assigned to planet Mercury. Citrine is said to be of help for backache.Diamond
Category Native Minerals
Chemical formula
C
Identification
Molar mass 12.01 g·mol-1
Color Typically yellow, brown or gray to colorless. Less often blue, green, black, translucent white, pink, violet, orange, purple and red.
In mineralogy, diamond (from the ancient Greek αδάμας – adámas "unbreakable") is anallotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions. Diamond is renowned as a material with superlative physical qualities, most of which originate from the strong covalent bonding between its atoms. In particular, diamond has the highest hardnessand thermal conductivity of any bulk material. Those properties determine the major industrial application of diamond in cutting and polishing tools.Diamond has remarkable optical characteristics. Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boron and nitrogen. Combined with wide transparency, this results in the clear, colorless appearance of most natural diamonds. Small amounts of defects or impurities (about one per million of lattice atoms) color diamond blue (boron), yellow (nitrogen), brown (lattice defects), green, purple, pink, orange or red. Diamond also has relatively high optical dispersion, that is ability to disperse light of different colors, which results in its characteristic luster. Excellent optical and mechanical properties, combined with efficient marketing, make diamond the most popular gemstone.The name diamond is derived from the ancient Greek αδάμας (adámas), "proper", "unalterable", "unbreakable, untamed", from ἀ- (a-), "un-" +δαμάω (damáō), "I overpower, I tame".[3] Diamonds are thought to have been first recognized and mined in India, where significant alluvial deposits of the stone could be found many centuries ago along the rivers Penner, Krishna and Godavari. Diamonds have been known in India for at least 3,000 years but most likely 6,000 years.[4]
Approximately 130 million carats (26,000 kg (57,000 lb)) of diamonds are mined annually, with a total value of nearly US$9 billion, and about 100,000 kg
Roughly 49% of diamonds originate from central and southern Africa, although significant sources of the mineral have been discovered in Canada, India, Russia, Brazil, and Australia.[40] They are mined from kimberlite and lamproite volcanic pipes, which can bring diamond crystals, originating from deep within the Earth where high pressures and temperatures enable them to form, to the surface. The mining and distribution of natural diamonds are subjects of frequent controversy such as concerns over the sale of blood diamonds or conflict diamonds by African paramilitary groups.[41]The diamond supply chain is controlled by a limited number of powerful businesses, and is also highly concentrated in a small number of locations around the world. In the U.S., diamonds have been found in Arkansas, Colorado, and Montana.[48][49] In 2004, the discovery of a microscopic diamond in the U.S. led to the January 2008 bulk-sampling of kimberlite pipes in a remote part of Montana.[49]
Today, most commercially viable diamond deposits are in Russia (mostly in Sakha Republic, for example Mir pipe and Udachnaya pipe),Botswana, Australia (Northern and Western Australia) and the Democratic Republic of Congo.[50] In 2005, Russia produced almost one-fifth of the global diamond output, reports the British Geological Survey. Australia boasts the richest diamantiferous pipe, with production from theArgyle diamond mine reaching peak levels of 42 metric tons per year in the 1990s.[48][51] There are also commercial deposits being actively mined in the Northwest Territories of Canada and Brazil.
Emerald is the most precious stone in the beryl group. The name emerald comes from the Greek "smaragdos" via the Old French "esmeralde", and really just means 'green gemstone.' The wonderful green color of emerald is unparalleled in the gem world. It is not surprising then that emerald is classified as one of the traditional four precious stones along with sapphire, ruby and diamond. Emerald is thebirthstone for May and for commemorating the 20th and 35th wedding anniversaries.Emerald's precious green color is caused by trace amounts of chromium and vanadium. Emerald, by definition, is a medium or darker green to blue green beryl, in which the green color is derived from impurities of chromium, vanadium, or a combination of both. The most popular and valuable color is a slightly bluish green in a medium dark tone with strong to vivid saturation. The
term "Colombian" emerald is often been used to describe vivid, slightly bluish green stones of medium, to medium dark color, no matter what their actual geographic origin. Emeralds of lighter color are sometimes called "Brazilian" emerald, even if they were mined in Africa. Emerald mining is nearly exclusively from host rocks, where the emerald has grown into small veins or on walls of cavities. Colombia is the world center of mining emerald. The Muzo mine, northwest of Bogotá, produces fine-quality stones of a deep green color. The Chivor mine, northeast of Bogotá, is another important deposit, other locations promise additional successful mining results. Brazil has various deposits in Bahia, Goias and Minas Gerais. The stones are lighter than the Colombian ones, mostly yellow-green and are often free of inclusions. Brazil also supplies rare emerald cat's eyes and extremely rare emeralds with a six-ray star. South Africa deposits concentrate in the northern Transvaal. But only five percent of the stones found in the Cobra and Somerset Mines are of good quality. Most stones are light or muddy and only suitable for cabochon cuts. Zimbabwe has several deposits of emerald; the most important is the Sandawana mine in the south. The crystals are small, but of very good quality. Russia has deposits in the Ural north of Sverdlovsk. Good qualities are rare; most stones are light or muddy and only suitable for cabochons. Further deposits are in Afghanistan, Australia (New South Wales, Western Australia), Ghana, India, Madagascar, Malawi, Mozambique, Namibia, Nigeria, Pakistan, Tanzania, Zambia and the United States (North Carolina). Common Emerald treatments Oiling is a common treatment of emerald. This term refers to the practice of immersing emeralds in a colorless oil or resin. Often this is done using a vacuum chamber to assist penetration. Non-standard treatments go beyond this to using green colored oils and hardened, epoxy-like resins. These treatments dramatically improve the appearance of the gems, but necessitate special care in cleaning and setting. Steam cleaners, solvents and ultrasonic can remove the oils, making inclusions that had barely been visible stand out in sharp relief. That damage is temporary only, since emeralds can be re-oiled.Emerald gemology Species: Beryl Color: Emerald green, green, slightly yellowish green Chemical composition: Al2Be3Si6O18, aluminum beryllium silicate Crystal system: (Hexagonal), hexagonal prisms Hardness: 7.5-8 (Mohs scale)
Specific gravity: 2.67 - 2.78 Refractive index: 1.565 - 1.602 Birefringence: -0.006 Color of streak: White Emerald is the birthstone for those who are born in May. Emerald is the gemstone for commemorating the 20th and 35th wedding anniversaries. Fire opal
Category Mineraloid
Chemical formula Hydrated silica. SiO2·nH2O
Identification
Color White
Crystal habit Irregular veins, in masses, in nodules
Crystal system Amorphous[1]
Cleavage None[1]
Fracture Conchoidal to uneven[1]
Mohs scalehardness
5.5–6.5[1]
Fire opal is an unusual variety of opal from Mexico. You will find two main types of fire opal. One is a translucent yellow, orange or red with no play of color. The other is brownish and has a play of color somewhat similar to the better known precious opal. Fire opals, like all opals, are delicate gemstones, sensitive to stress. Thus they are best suited for earrings, brooches, and pendants and need to be treated carefully The colors range from yellow to orange to brown and red. The best stones
usually show a vivid burnt red-orange combination Opals are delicate gemstones. Their most significant weakness has to do with their water content. If an opal is allowed to dry, it will crack and fade. If you live in a very dry climate, or keep them in a dehumidified room, some precautions are necessary. Keeping them in a tight plastic bag, with a damp piece of cotton or fabric will prevent dehydration. Because of their water content, opals are also sensitive to sudden changes in temperature. Being somewhat soft, they scratch easily. Realize that a large component of ordinary dust is quartz at 7 on the (Mohs scale) of hardness. At 5.5 to 6 in hardness, simply wiping the dust off an opal will gradually reduce its polish. The solution is to clean your opals using a soft cloth. The finest fire opals are found in Mexico. Other deposits are in Brazil, Guatemala, the United States and Australia.Fire opals is usually untreated. It is reported to be able to solve depressions and to help its wearer find the true and real love. Opal is the birthstone for those who are born in October. Garnet
Category Mineral
Chemical formula
Ca3Al2(SiO4)3
Identification
Color light to dark green, light to dark yellow to reddish brown, occasionally translucent to opaque pink. It is also but rarely found in colorless
Single refractive, often anomalous double refractive [1]
Refractive index 1.740 (+.12 -.04) [1]
Garnet is derived from the Latin word "granum" meaning "grain". This refers to the typically rounded shape of Garnet and also reminiscent of the seeds of the pomegranate. Garnets have been widely known for thousands of years. Even Noah, it is reported, used a lantern from garnet in order to safely steer his Ark through the darkness of the night. Although the color red occurs most frequently, there are also garnets showing different shades of green, pale to bright yellow, fiery orange and fine earth- and umbra-shades. Only blue is the color that is not available in Garnet. Garnet colors Although the color red is occurs most frequently, there are also garnets showing different shades of green, pale to bright yellow, fiery orange and fine earth- and umbra-shades. Blue is the only color that is not available in Garnet. Color change garnets are mostly pyrope and spessartite in composition. The colorful members of the garnet group:
Pyrope, red garnet, frequently with brown tint Rhodolite, purplish red or rose-color garnet Almandite, red garnet with violet tint Spessartite, orange to red-brown garnet. The best specimen comes from Namibia and is called "Mandarin Spessartine". Grossularite, colorless, green, yellow, brown garnet Hydrogrossular, dense, opaque greenish variety of grossularite Hessonite, brown-red variety of garnet Leuco garnet, colorless variety of grossularite Tsavorite, green to emerald green garnet Andradite, black, brown, yellow-brown garnet Demantoid, the most valuable garnet, green to emerald green Melanite, opaque black variety of andradite Tapazolite, yellow to lemon yellow, topaz-like variety of andradite Uvarovite, emerald green garnet that rarely occurs in gemstone quality. garnet location and deposits Pyrope: China, Madagascar, Myanmar, South Africa, Sri Lanka, Tanzania, USA Rhodolite: Brazil, India, Sri Lanka, Thailand, USA Almandite: Brazil, India, Madagascar, Sri Lanka and the United States. Smaller deposits exist in Austria and the Czech Republic. Almandine garnet star-stones are found in India and the United States (Idaho). Spessartite: Brazil, China, Kenya, Madagascar, Myanmar, Namibia, Sri Lanka, Tanzania, USA. The best specimens come from Namibia and are called "Mandarin Spessartine (Spessartite) " Grossularite: Canada, Kenya, Mali, Pakistan, Russia, South Africa, Sri Lanka, Tanzania, USA Hydrogrossular: Myanmar, South Africa, Zambia Hessonite: Brazil, Canada, Madagascar, Sri Lanka, Tanzania, USA Leuco garnet: Canada, Mexico, Tanzania Tsavorite: Kenya, Tanzania Andradite: Russia Demantoid: China, Korea, Russia, USA, Zaire Melanite: France, Germany, Italy, USA Tapazolite: Italy, Switzerland, USA Uvarovite: Canada, Finland, India, Poland, Russia, USA Garnet is the birthstone for those who are born in January. On the Zodiac chart, it is listed as the stone for Aquarius.Garnet is said to be of help for arthritis, pancreas, varicose veins and problems with testicles and toenails. Hematite
Hematite, an iron oxide, derives its name from the Greek word for blood, since it is red when sliced thinly or powdered. Hematite crystallizes in the rhombohedral crystal system, and has the same crystal structure assapphire and ruby. Hematite is always opaque and is typically a blackish grey. You will find it cut as cabochons or faceted, and engravings are particularly popular. Hematite was a traditional material for signet rings. When highly polished it can sometimes look like silver.
Idocrase is a rare gemstone, usually found in shades of green but sometimes in yellow-brown or pale blue. Idocrase belongs to the silicate group of minerals. While the name idocrase is used for rare gemstone-quality specimens, the mineral is usually known by the name vesuvianite, since the first samples were found on the Mt. Vesuvius volcano. Idocrase is not only rare, but transparent specimens that can be faceted count as very rare indeed. Most gem-quality idocrase is opaque with an appearance similar to jade. The opaque specimens have a greasy or resinous luster, while the rare transparent form has a vitreous luster Idocrase or vesuvianite is found in a number of locations in the world. They include Quebec in Canada, Mt. Vesuvius in Italy, the Ural Mountains in Russia, Switzerland, Kenya and Tanzania. But there are very few sources of gem-quality crystals. Recent finds in Kenya and Tanzania have brought some very fine stones to the market, albeit in limited quantity. One source of cabochon grade material is California, USA. It has been marketed as Californite or California Jade. Topaz
Category Silicate mineral
Chemical formula
Al2SiO4(F,OH)2
Identification
Color Clear (if no impurities), blue, brown, orange, gray, yellow, green, pink and reddish pink.
Topaz comes in many colors, including clear, brown, yellow, orange, red, pink and blue. The blue topaz, with a pale to medium blue color created by irradiation, can be found in very large sizes at affordable prices. The fine golden-yellow variety, known as Imperial Topaz, is relatively scarce. Topaz colors are rarely vivid. The most common color is yellow with a red tint; the most valuable is pink to reddish. The coloring agents are iron and chromium. The name topaz is most probably derived from an island in the Red Sea, "Topazos", today called Zabargad, the ancient source of peridot. In former times all golden-brown and sometimes also green gemstones were called topaz, which caused sufficient confusion such that today real topaz is referred to as precious topaz. Topaz comes in many colors, including clear, brown, yellow, orange, red, pink and blue. The blue topaz, with a pale to medium blue color created by irradiation,
can be found in very large sizes at affordable prices. The fine golden-yellow variety, known as Imperial Topaz, is relatively scarce. Topaz colors are rarely vivid. The most common color is yellow with a red tint; the most valuable is pink to reddish; the most popular is blue. The coloring agents are iron and chromium. Blue topaz: Natural blue topaz is rare. Found in all major deposits and also in England (Cornwall), Northern Ireland and Scotland. Most of the blue topazes are enhanced colorless topaz gemstone (see common treatment) Champagne topaz: One of the very few naturally colored varieties of topaz in a light to medium shade of brown, primarily found in Mexico. Imperial topaz: The most sought after of all natural topaz. Its rich golden color is generally not enhanced by any kind of treatment. The most important deposit was found in Minas Gerais, Brazil. Pink topaz: A natural pink topaz is very rare and costly. The vast majority of pink topazes are heat-treated yellow stones that turn pink. The most valuable variety of topaz can be found in Brazil, Pakistan and Russia. Brazil (Minas Gerais) is the most important supplier for topaz. Other deposits are in Afghanistan, Australia, China, Japan, Madagascar, Mexico, Myanmar, Namibia, Nigeria, Pakistan, Russia, Sri Lanka, Ukraine, United States and Zimbabwe. Natural light blue topaz is also found in England (Cornwall), Northern Ireland and Scotland. Blue topaz begins as colorless or very lightly tinted natural topaz crystals, which are then irradiated to change the color to blue and heated to stabilize the change. Neutron bombardment in a nuclear reactor produces the deep slightly greenish or grayish "London Blue", while electron bombardment in a linear accelerator results in the light aqua-like blue known as "Sky Blue". Combinations of both treatments produce the highly saturated "Swiss" and "Electric" blues. If neutron bombardment has been used, there is residual radioactivity, and the gems must be held, up to a year, before they have "cooled" enough to be worn. In general, blue topaz is modestly priced. Due to the expenses of reactor time the London Blue color is short in supply and climbs in value. In early 1998, a new type of enhanced topaz made its appearance, the surface-enhanced topaz, with colors described as blue to greenish-blue or emerald green. The vast majority of pink topazes are heat-treated yellow stones that turn pink. Topaz is the birthstone for those who are born in the month of November. Iolite
Refractive index nα = 1.527 - 1.560 nβ = 1.532 - 1.574 nγ = 1.538 - 1.578 Indices increase with Fe content.
Kunzite Kunzite is the pale pink-violet to light violet species of the mineral spodumene.Kunzite is named as a tribute to George F. Kunz, the legendary American mineralogist and buyer for Tiffany & Co, who first described the gem in 1902. Kunzite is the pink-violet sister to the yellow-green hiddenite, another specimen of the spodumene family. Kunzite is strongly pleochroic, meaning there is a color intensity variation when a crystal of it is viewed from different directions. The top and bottom of the crystal reveal the deepest colors. Kunzite is very difficult to cut to ensure that the light passes trough the gem and accents the desired color. Kunzite is said to help one to understand and interact better with others.
Kunzite is a transparent gem, but can show frequently aligned inclusions such as tubes or fracture. An eye clean gem would be the best choice.Species: Spodumene Color: Pink-violet, light violet Chemical composition: LiAlSi206 lithium aluminum silicate Crystal system: Monoclinic, prismatic, tabular Hardness: 6.5 - 7 (Mohs scale) Specific gravity: 3.15 - 3.21 Refractive index: 1.660 - 1.681 Birefringence: +0.014 to +0.016 Color of streak: White, Absorption spectrum: Not diagnostic Fluorescence: Strong: yellow-red, orangeThe Kunzite zodiac, myth & legend Some consider kunzite a modern-day birthstone for February, which lacks support of the traditionalists. The wearer of a kunzite gemstone is believed to be blessed with good fortune. Kunzite is said to help one to understand and interact better with others.In Antiquity, as well as in the Middle Ages people believed that the cosmos is reflected in gemstones. Kunzite is assigned to the planets Pluto and Venus. Kyanite Kyanite is named after the Greek word for "blue". Its color indeed can make it a lovely gem with a near sapphire-like blue. Usually its color is blue but also can be colorless, white, gray, green or yellow. Color is often not consistent throughout the crystal, often showing white streaks in a medium blue. Luster is vitreous to almost pearly. It's a nice gemstone for earrings or pendants. Kyanite is believed to aid self-expression, communication and supernatural abilities. The most desired color would be a sapphire-like blue. Colorless stones are quite rare. Kyanite location and deposits Deposits are found in Austria, Brazil, India, Kenya, Myanmar, Serbia, Switzerland, United States and Zimbabwe. Kyanite gemology Species: Kyanite Color: Blue to colorless, blue-green, brown Chemical composition: Al2SiO5 aluminum silicate Crystal system: Triclinic, long, flat prisms Hardness: Along axes 4 - 4.5, across 6-7 (Mohs scale) Specific gravity: 3.53 - 3.70 Refractive index: 1.710 - 1.734
Birefringence: -0.015 Color of streak: White, Absorption spectrum: 706, 689, 671, 652, 446, 433 Fluorescence: Weak: red In ancient times it was believed that a kyanite suspended from a human hair could fallow the Earth's magnetic force like a compass needle. In those times travelers took kyanite along with them, when they entered unknown territories. Labradorite Labradorite is an iridescent gemstone with a fascinating schiller or metallic luster when viewed from certain angles. A member of the plagioclasefeldspar group along with andesine and sunstone.The ground color oflabradorite is a dark smoky gray, but when light strikes the stone in a particular direction, it displays striking rainbow-colored reflections. Most typically, these metallic tints are violet, blue and green; but sometimes yellow, orange and red can be seen. This effect is so unique to labradorite that it is referred to as labradorescence.The labradorescent effect is believed to be due to the presence of very fine platelets of different compositions as well as minute inclusions of limenite, rutile and possible magnetite which cause the diffraction of light.Labradorite was named after the Labrador Peninsula in eastern Canada where it was first found around 1770. Deposits have also been found in Australia, Finland, Madagascar, India, Mexico and the Adirondack Mountains in the United States.labradorite is reasonably hard at 6 to 6.5 on theMohs scale Lapis Lapis Lazuli is used for more than 6000 years for jewelry and ornamental objects. Its name is from "lapis," the Latin word for stone and "azul," the Arabian word for blue. Lapis lazuli is made up of 25 to 40 percent lazurite, plus several minerals (sodalite, hauyne, calcite, and pyrite) that influence color and its distribution. Based on that varying composition, lapis lazuli is considered a rock, not a mineral.Lapis Lazuli defines its color by name, the blue stone. Its blue varies from lazur blue, to violet and greenish-blue. Its coloring agent is sulfur. In the very best quality stones the color is evenly distributed, but in general the color is spotted.The composition of the minerals, other than lazurite, influences the color as well. Well-distributed fine pyrite highlights the color with a brassy gold shimmer. Too much of the same mineral causes a dull, greenish tint. Lapis Lazuli fans may not agree as to how much pyrite is ideal. But most admirers and collectors of fine lapis lazuli agree -- the less calcite, the better. Calcite can be seen as streaks or patches within the darker blue, or it can predominate in the mix giving the rock an overall lighter blue shade.
Lapis lazuli is opaque, with a vitreous and greasy luster. The oldest deposits, discovered 6000 years ago, are located in the difficult terrain of the West Hindu-Kush Mountains in Afghanistan. They still produce the finest quality. Other deposits have been found in Angola, Canada, Chile (North of Santiago), Myanmar, Pakistan, Russia (Lake Baikal) and the United States (California and Colorado). Lapis Lazuli gemology Species: Lapis Lazuli Color: Lazur-blue, violet, greenish-blue Chemical composition: (Na,Ca)8(SiO4,S,CI)2I(AlSi)4l6 sodium calcium aluminum silicate Crystal system: Cubic (rare), dense aggregates Hardness: 5-6 (Mohs scale) Specific gravity: 2.50 – 3.00 Refractive index: About 1.50 Birefringence: None Color of streak: Light blue For people around the world, lapis lazuli is considered a stone of truth and friendship. The blue stone is reputed to promote harmony in relationships.In Antiquity, as well as in the Middle Ages, people believed that the cosmos was reflected in gemstones. Lapis lazuli is assigned to the planet Jupiter. The esoteric movement revived the ancient believe and the gem industry made it another marketing tool to promote certain gems.The healing powers of gems remain a controversial issue, but are mentioned for centuries by healers, shamans and medicine men. Whether it’s a fact or a placebo effect doesn’t matter, if it helps. Lapis lazuli is said to be of help for headaches, sore throat and varicose veins. MoonstoneMoonstone owes its name to the white, almost magical shimmer that resembles moonshine. Blue-whitish light glides over the surface when the stone is cut cabochon. Gemologists call this phenomena adularescence, which originates from the interior structure of the gemstone in scales or lamellas. Incoming rays of light are refracted inside the stone and scattered, creating a unique play of light, which makes Moonstone so special and coveted.Moonstone is the most well known potassium feldspar of the orthoclasespeciesIn Arab countries women often sew moonstone into their garments, because it's considered a symbol of fertility.Moonstone is the birthstone for those who are born in June.Moonstone from Sri Lanka, the classical country of origin for Moonstone,
shimmers pale blue on an almost transparent ground. Specimens from India show cloudlike plays of light and shade on beige brown, green, orange, or simple brown background. They do come as well in blue and peach, smoke and champagne colored, or in black and reddish.Deposits are found in Brazil, India, Madagascar, Myanmar, Sri Lanka and the United States.Moonstone gemology Species: Feldspar Color: Colorless, yellow, pale sheen Chemical composition: KalSi3O8 potassium aluminum silicate Crystal system: Monoclinic, prismatic Hardness: 6-6.5 (Mohs scale) Specific gravity: 2.56 - 2.59 Refractive index: 1.518 - 1.526 Birefringence: -0.008 Color of streak: White, Absorption spectrum: Not diagnostic Fluorescence: Weak; bluish, orange OnyxIt’s a type of Chelcedony so please refer to chalcedony. PeridotPeridot belongs to the forsterite-fayalite mineral series, which is part of the olivine group. It is one of the "idiochromatic" gems, meaning its color comes from the basic chemical composition of the mineral itself, not from minor impurities, and therefore will only be found in shades of green. As a matter of fact peridot is one of the few gemstones found in only one color.The name peridot most probably derives from the Arabic word "faridat" for gem. It's also called chrysolith (derived from the Greek word "goldstone") and olivine, because of its color and membership to the olivine group. Historically the volcanic island Zabargad (St. John) in the Red Sea, east of Egypt, was the most important deposit that was exploited for 3500 years. Today's main deposits are in Arizona, China, Vietnam and Pakistan. The Pakistani peridot in particular is very fine, and a new find in Pakistan in the mid-1990's has made peridot available to a wider market.Historically the volcanic island Zabargad (St. John) in the Red Sea, east off Egypt, was the most important deposit that was exploited for 3500 years, abandoned for many centuries, rediscovered only around 1900 and has been completely exploited since. The most important deposits nowadays are found in Pakistan (Kashmir region and Pakistan-Afghanistan border region) and is regarded as being of the finest quality. Beautiful material is also found in
upper Myanmar and Vietnam. Other deposits have been found in Australia (Queensland), Brazil (Minas Gerais), China, Kenya, Mexico, Norway (north of Bergen), South Africa, Sri Lanka, Tanzania and the United States (Arizona and Hawaii).Peridot gemology Species: olivine Color: Yellow-green, olive-green, brownish Chemical composition: (Mg,Fe)2SiO4 magnesium iron silicate Crystal system: Orthorhombic; short compact prisms, vertically striated Hardness: 6.5-7 (Mohs scale) Specific gravity: 3.28 - 3.48n ancient believes peridot was a gift of Mother Nature to celebrate the annual creation of a new world. National leaders who publicly wore peridot were in former times thought to be gentle, fair and wise.In Antiquity, as well as in the Middle Ages people believed that the cosmos is reflected in gemstones. Peridot is assigned to planet Saturn. The esoteric movement revived the ancient belief and the gem industry made it another marketing tool to promote certain gems. PrehniteHundreds of minerals have been named after individuals, including a number of gemstones. The gemstones include Hiddenite (W.E. Hidden), Kunzite(George Frederic Kunz), Morganite (J.P. Morgan) andZoisite (Sigmund Zois).But there is one gemstone that has the distinction of being the very first mineral ever named after an individual. The gemstone Prehnite was named for its discoverer, Colonel Hendrik von Prehn (1733-1785), a Dutch mineralogist and an early governor of the Cape of Good Hope colony.Prehnite was also the very first mineral to be named and described from South Africa, long before South Africa became an important source for precious gems.Prehnite is a hydrated calcium aluminum silicate that occurs in a soft yellow-green to apple-green color. Many specimens have an intriguing luminous quality. It has a vitreous to mother-of-pearl luster. Prehnite is a medium-hard gem with a rating of 6 to 6.5 on the Mohs scale. Most prehnite is translucent but transparent specimens are sometimes found. Prehnite has a density or specific gravity of 2.82-2.94 and a refractive index of 1.611-1.669.Deposits are found in South Africa, Australia, China, Scotland and the United StatesPrehnite is said to encourages composure, forgiveness and acceptance and is excellent for meditation. Some people also believe that prehnite helps sufferers of claustrophobia. Quartz
Quartz is one of the most common minerals on earth and is well known in the gems world. Quartz is attractive and durable, as well as inexpensive. It can be cut and carved in many forms and sizes. Quartz is named after a Slavic word for "hard". There are two main varieties of quartz, though they share the same chemical composition, silicon dioxide. Macrocrystalline quartz, includes stones likeamethyst, aventurine, rock crystal, blue quartz, citrine, hawk's eye, prasiolite, quartz cat's eye, smoky quartz, rose quartz and tiger's eye. The quartz is mostly transparent to translucent. Cryptocrystalline quartz, with microscopically small crystals, is known as chalcedony, and includes agate, chrysoprase, bloodstone, jasper and carnelian. Crytocrystalline quartz is usually opaque or translucent.The colors of macrocrystalline quartz are as follows: Rock crystal: Colorless. Material that can be cut is rare. Inclusions are of goethite, gold, pyrite, rutile or tourmaline. The luster is vitreous. Smoky quartz: Brown to black, smoky gray. The coloring is caused by natural and artificial gamma rays. Frequent inclusions are rutile needles. Amethyst: Purple, violet, pale red-violet. Amethyst is the most highly valued stone in the quartz group. The coloring agent is iron. Amethyst Quartz: Violet with whitish stripes. Amethyst quartz is a more compact formation of amethyst, layered and striped with milky quartz. Ametrine: Yellow and violet. Color-zoned quartz variety that consists half of amethyst and citrine. Citrine: Light yellow to dark yellow, gold-brown. The coloring agent is iron. Many commercial citrines are heat-treated amethyst. Natural citrines are mostly pale yellow. If heat-treated they acquire a reddish tint. Prasiolite: Leek-green. Prasiolite is not found in nature. Prasiolite is produced by heat treatment of amethyst or yellowish quartz. Rose quartz: Strong pink, pale pink. Coloring agent is titanium. Traces of included rutile needles cause six-rayed stars when cut en cabochon. Larger clear stones can be faceted. Rose quartz crystals tend to be cloudy, which deepens the color. Transparent crystals are extremely rare. Aventurine: Green, red-brown, gold-brown. Mostly dark green with metallic glittery appearance caused by included fuchsite (green mica), or red- to gold-brown caused by hematite leaves. Prase: Leek-green. Prase is a quartz aggregate, usually classified as a
chalcedony whose color agent are chlorite inclusions. Blue quartz: Turbid blue. Inclusions of crocidolite fibers cause the color. Quartz cat's eye: White, gray, green, yellow, brown (Cat's eye: Is a reflection of light by parallel fibers, needles, or channels, which resembles the slit eye of a cat. When the stone is rotated, the cat's eye glides over the surface.) Hawk's eye: Blue-gray to blue green (Hawk's eye: Small ray of light on the surface that is reminiscent of the eye of a bird of prey) Tiger's eye: Gold-yellow, gold-brown (Similar to Hawk's eye effect, ray of light is brown colored due to oxidized iron inclusions)The colors of cryptocrystalline quartz: In the narrow sense, chalcedony (species name for all cryptocrystalline quartzes) will mean any translucent, cryptocrystalline quartz with a single color, whether it has a special variety name or not. Its colors are bluish, white, or gray. The various types differ in color due to metallic impurities, such as iron, nickel, copper, and titanium, present during crystallization. Agate is distinguished by having multiple colors. Banded agates are some of the most popular. A rarity is the so-called fire agate. Fire agate: The iridescent colors of red, gold, green and rarely, blue-violet, result from interference between light rays traveling through these thin layers. Agate jasper, which grows together with agate, is yellow, brown, or green blended. Agate comes in many different trade names. The most important ones are: Dendritic agate: Colorless or whitish, translucent chalcedony with tree- or fern-like markings (called dendrites). Moss agate: Colorless with green, brown or red inclusions. Moss agate is a translucent chalcedony with moss-like inclusions of hornblende or chlorite. Scenic agate: Agate where the included dedrites resemble landscape-like images in brown or reddish color tones. Onyx is a layered stone with a black base and a white upper layer. Bloodstone is an opaque, dark-green chalcedony with red spots (caused by iron oxide). Blue chalcedony, called "Mohave" and "Mt. Airy Blues", originate in California and Nevada, are slightly to moderately grayish blue with a light to medium color range. Blue chalcedony from Namibia, often called "African Blue", varies from grayish to nearly pure blue and from light to medium dark. The most unusual and most valuable type is from Oregon. Its blues are modified by slight to moderate amounts of pink, making a noticeably lavender gem, which nonetheless is called "Holly Blue." Chalcedony, in the narrow sense, comes in bluish white or gray. Unicolored chalcedony sometimes is called onyx.
Carnelian ranges in color from yellow-orange to rich, near reddish orange, to orangey brown, and varies from semi-opaque to highly translucent. The color agent is iron. The color can be enhanced by heating. Cornelian onyx is a layer stone with a red base and a white upper layer. Chrysoprase, apple green chalcedony that derives its color from nickel, is ranging from nearly opaque to nearly transparent. Its color spectrum includes olivey, to nearly pure greens of medium tone. Very fine, highly saturated pieces have been successfully misrepresented as Imperial jade. Chrysocolla Chalcedony, marketed as "Gem Silica" this relatively rare, blue to blue-green, opaque to near transparent material is the most expensive type of chalcedony. Its color agent is copper.Quartz location and deposits Quartz is one of the most common minerals on earth. Macrocrystalline quartz deposits: Rock crystal: In the Alps, Brazil, Madagascar, United States Smoky quartz: Brazil, Madagascar, Russia, Scotland, Switzerland, Ukraine Amethyst: Brazil, Bolivia, Canada, India, Madagascar, Mexico, Myanmar (Burma), Namibia, Russia, Sri Lanka, United States (Arizona), Uruguay and Zambia Amethyst quartz: Brazil, Bolivia, Canada, India, Madagascar, Mexico, Myanmar (Burma), Namibia, Russia, Sri Lanka, United States (Arizona), Uruguay and Zambia Ametrine: Brazil, Bolivia Citrine: Argentina, Brazil, Madagascar, Namibia, Russia, Scotland, Spain, United States Prasiolite: Brazil, United States (Arizona) Rose quartz: Brazil, India, Madagascar, Mozambique, Namibia, Sri Lanka, USA Aventurine: Austria, Brazil, India, Russia, Tanzania Prase: Austria, Finland, Germany, Scotland Quartz cat's eye: Brazil, India, Sri Lanka Hawk's eye: Brazil, India, Sri Lanka Tiger's eye: Australia, India, Myanmar, Namibia, South Africa, Sri Lanka, United StatesCryptocrystalline quartz deposits: Australia: Agate, chrysoprase, bloodstone Brazil: Agate, chalcedony, carnelian, bloodstone, chrysoprase China: Agate, bloodstone India: Agate, chalcedony, bloodstone, carnelian, chrysoprase Kazakhstan: Chrysoprase Madagascar: Agate, chalcedony, chrysoprase Mexico: Agate Mongolia: Agate
Namibia: Agate, blue chalcedony, chalcedony, Russia: Chrysoprase Sri Lanka: Chalcedony, Uruguay: Agate, chalcedony, carnelian South Africa: Chrysoprase Tanzania: chrysoprase Zimbabwe: Chalcedony, chrysoprase USA: Agate (Montana and Wyoming), chalcedony (California), chrysocolla chalcedony (Arizona), bloodstone, blue chalcedony (California, Nevada, Oregon)Common Quartz treatments Colorless quartz is always untreated. Colored stones can occasionally be enhanced in color by dying (as in the case of agate), irradiation (bombardment with low level radioactivity), or heating. Reliable gem dealers will always inform their customers about any kind of treatment.Quartz gemology Species: Macrocrystalline Quartz Chemical composition: SiO, silicon dioxide Hardness: 7 (Mohs scale) Specific gravity: 2.65 The Quartz zodiac, myth & legend Leonardo da Vinci wrote that amethyst, the most valuable stone in the quartz family, was able to dissipate evil thoughts and quicken the intelligence.Rock crystal and smoky quartz were once used for crystal balls that disclosed fortunetellers, witches or gypsy grandmas the future of their clients.Amethyst is the birthstone for those who are born in February, while Citrine is a birthstone for November.In Antiquity, as well as in the Middle Ages people believed that the cosmos is reflected in gemstones. The amethyst is assigned to planet Neptune. Citrine is assigned to planet Mercury as well as tiger's eye. Rose quartz is assigned to planet Venus. Chalcedony is assigned to Planet Saturn. Smoky quartz is assigned to planet Pluto. The esoteric movement revived the ancient belief and the gem industry made it another marketing tool to promote certain gems.The healing powers of gems remain a controversial issue, but are mentioned for centuries by healers, shamans and medicine men. Whether it's a fact or a placebo effect doesn't matter, if it helps. The safest approach is to wear the gemstone in skin contact to the troubled part of the body. Quartz is said to be of great helping potential. Headaches: Amethyst, rock crystal, tiger's eye Eye inflammation: Rock crystal, chalcedony, hawk's eye, onyx Sore throat: Rock crystal Heart ailments: Rose chalcedony, rose quartz Pancreas: Amethyst, citrine, yellow jasper Sciatica: Amethyst, citrine, rose quartz, tiger's eye Varicose veins: Rock crystal
Toenails: Rose quartzRhodolite GarnetRhodolite Garnet is the name applied to a mixture of almandite and pyrope. Most probably the name rhodolite comes from the Greek word, "rhodon", meaning rose. The excellent hardness of 7 to 7.5 on the Mohs scale makes garnet suitable for all kinds of jewelry. Garnet is the January birthstone.Rhodolite Garnet location and deposits Deposits are found in Brazil, India, Sri Lanka, Tanzania, Thailand and the USA {North Carolina).Species: Garnet Color: Red with violent tint Chemical composition: Fe3Ai2 (Sio4)3 iron, aluminum, silicate Crystal system: (Cubic), rhombic dodecahedron, icons tetrahedron Hardness: 6.5 - 7.5 (Mohs scale)RubyRuby is red corundum, all other color varieties of corundum being referred to as sapphireRuby is named after the Latin word "ruber" for red. Rubies range in color from pinkish to orangey and purplish and brownish red, depending on the chromium and iron content of the stone. The most desirable color is the so-called "pigeon's blood", a pure red with a hint of blue, only found in the mines of Myanmar (Burma), the most important ruby deposits known. Ruby is one of the most expensive gems, large rubies being rarer than comparable diamonds. Many rubies are an essential part of royal insignia and other famous jewelry. Ruby is the birthstone for those who are born in July. Ruby is also used to celebrate a couple's 15th and 40th anniversary.Ruby location and deposits Myanmar: For centuries the most important deposits are in upper Myanmar (Burma) near Mogok. Only one percent of the production is of gem quality. Some of the rubies are of pigeon's blood color and considered to be the most valuable rubies of all. In the early 1990's large new deposits were discovered at Mong Hsu. Thailand: Rubies found in Thailand (Chanthaburi district) often have a brown or violet tint. The Thai ruby production is declining, and Chanthaburi is now mainly a center for processing and trading gems. Sri Lanka: The deposits are located in the southwest of the island in the Ratnapura district. Rubies from that deposits are usually light red to raspberry red.
Tanzania: On the upper Umba River in northwest Tanzania are deposits for gemstone quality rubies that are violet to brown-red. A few opaque rubies are mined as well. Other deposits of some importance are found in: Afghanistan, Cambodia, Kenya, Madagascar and Vietnam. Less significant deposits are in: Australia, Brazil, India, Malawi, Nepal, Pakistan, United States and Zimbabwe.Common Ruby treatments The most common treatment for ruby is heat treatment. Stones, generally before they are cut, are heated to between 1700 to 1800 degrees Celsius (3100-3300 degrees F) for several hours. Heating often improves both color and clarity. A reputable dealer will always disclose gem treatments.Lower grade rubies with surface-reaching fissures are often fracture-filled with lead glass. This treatment produces good looking stones that can be sold at a very reasonable price.Ruby gemology Species: Corundum Color: Varying red Chemical composition: Al2O3 aluminum oxide Crystal system: (Trigonal) hexagonal prisms or tables, rhombohedrons Hardness: 9 (Mohs scale)For a long time India was considered as the classical source of rubies. In the Sanskrit language ruby is called "ratnaraj", which translates as "King of Gemstones". In ancient times one of the chief attractions of ruby has been its protection from misfortune and bad health. Ruby is the birthstone for those who are born in July. On the Zodiac chart, ruby is the stone for Capricorn.Ruby is also used to celebrate a couple's 15th and 40th anniversary.In Antiquity, as well as in the Middle Ages people believed that the cosmos is reflected in gemstones. The ruby is assigned to the planets Mars and Pluto. Ruby-ZoisiteRuby-Zoisite, also known as anyolite, is the natural combination of ruby and zoisite crystals in a single specimen. Zoisite, the same mineral as tanzanite, provides an earthy green and black color while ruby lends pink and red highlightsRuby-Zoisite was first discovered in 1954 in Tanzania. The name anyolite derives from the word for "green" in the native language of the Massai. Ruby-Zoisite gemology Species: Zoisite
Color: Green with black and opaque ruby inclusions Chemical composition: Ca2Al3(Sio4)3(OH) calcium aluminum silicate Crystal system: Orthorhombic, multifaced prisms, mostly striated Hardness: 6.5-7 (Mohs scale)Rutilated Quartz
Rutile is a mineral composed primarily of titanium dioxide, TiO2.
Rutile is the most common natural form of TiO2. Two rarer polymorphs of TiO2 are known:
§ anatase (sometimes known by the obsolete name 'octahedrite'), a tetragonal mineral of pseudo-octahedral habit; and
§ brookite, an orthorhombic mineral.
Rutile has among the highest refractive indices of any known mineral and also exhibits highdispersion. Natural rutile may contain up to 10% iron and significant amounts of niobium andtantalum.
Rutile derives its name from the Latin rutilus, red, in reference to the deep red color observed in some specimens when viewed by transmitted light.
Rutile is a common accessory mineral in high-temperature and high-pressure metamorphic rocksand in igneous rocks.
Rutile is the preferred polymorph of TiO2 in such environments because it has the lowest molecular volume of the three polymorphs; it is thus the primary titanium bearing phase in most high pressure metamorphic rocks, chiefly eclogites. Brookite and anatase are typical polymorphs of rutile formed by retrogression of metamorphic rutile.
Within the igneous environment, rutile is a common accessory mineral in plutonic igneous rocks, although it is also found occasionally in extrusive igneous rocks, particularly those which have deep mantle sources such as kimberlites and lamproites. Anatase and brookite are found in the igneous environment particularly as products of autogenic alteration during the cooling of plutonic rocks; anatase is also found formed within placer deposits sourced from primary rutile.
The occurrence of large specimen crystals is most common in pegmatites, skarns and particularly granite greisens.
Rutile is found as an accessory mineral in some altered igneous rocks, and in certaingneisses and schists. In groups of acicular crystals it is frequently seen penetrating quartz as in the "fléches d'amour" from Graubünden, Switzerland.
In 2005 the Republic of Sierra Leone in West Africa had a production capacity of 23% of the world's annual rutile supply, which rose to approximately 30% in 2008. The reserves, lasting for about 19 years, are estimated at 259,000,000 metric tons (285,000,000 short tons).[5]
Color Reddish brown, red, pale yellow, pale blue, violet, rarely grass-green; black if high in Nb–Ta
Crystal habit Acicular to Prismatic crystals, elongated and
striated parallel to [001]
Crystal system Tetragonal ditetragonal dipyramidal
Twinning Comon on {011}, or {031}; as contact twins with two, six, or eight individuals, cyclic, polysynthetic
Cleavage {110} good, 100 moderate, parting on {092} and {011}
Fracture Uneven to sub-conchoidal
Mohs scalehardness
6.0 - 6.5
SapphireSapphire The blue sister of ruby. Ruby and sapphire are the same material, the mineral corundum, and the second hardest gemstone after diamond. Red corundum is known as ruby, while all other colors are referred to as sapphire. While blue is the classic sapphire color, sapphire is actually found in a wide range of colors, including yellow, pink and green.Sapphire colors Blue is the most famous of the sapphire colors. The prized Kashmir and Burmese sapphires have a deep blue that is intense and velvety. These sapphires are not often seen on the market today. Sri Lankan and Madagascar sapphires are the most common today, with a wide range of colors from light sky blue to dark blue. Other producers of blue sapphire are Australia, Tanzania, Thailand, Cambodia, and Montana.Colorless corundum is rare as faint shades of color are nearly always present. Many small white sapphires used in jewelry are synthetic.Purple sapphire is rare, but found in Sri Lanka and Tanzania. Iron and titanium impurities together may cause the purple hue of the stone.Much yellow sapphire is on the lighter side. Heat treatment can produce a more intense yellow golden color, and beryllium-treated sapphire may be a brilliant yellow. These stones are found in Sri Lanka, Thailand, Australia, Tanzania and Madagascar. The yellow color is caused by traces of iron in the stone.Padparadscha is the Sinhalese word for a Sri Lankan lotus flower. This very rare sapphire color should have a pink and orange color simultaneously. Color, brilliance, size and clarity will determine the value of these stones. A truepadparadscha will always have a hint of pink.Many sapphires that appear green consist of fine alternating bands of blue andyellow sapphire, which may be visible under the microscope. Green sapphiresare found in Thailand, Sri Lanka, Australia, and Madagascar.Sapphires come from Thailand, Sri Lanka, Madagascar, Tanzania and Australia. The United States, Cambodia, Nigeria, Kenya and China also produce some sapphires. Perhaps the most famous sources for sapphires are the Kashmir region of India, and Burma. Discovered over 100 years ago, the Kashmir sapphire has a lovely, velvety blue color prized by gem lovers. Burmese sapphires can also be fine, but like the Kashmir region, these two areas today
produce very little material.Today Sri Lanka and Madagascar produces most of the fine sapphires on the market. You can find a wide range of beautiful blues, from soft sky blue colors to deeply saturated hues. In addition, the Kanchanaburi region in Thailand and the Pailin region in Cambodia are renowned for deep blue sapphires. Tanzania, an old producer of sapphires in other colors, is now starting to produce blue sapphire from new deposits in the south.Common Sapphire treatments The most common treatment for sapphire is heat treatment. Stones are heated (generally before they are cut) to between 1700 to 1800 degrees Celsius (3100-3300 degrees F) for several hours. Most sapphires today are heated, and the stones of rich blue that are not heated can command enormous prices in today's market. Some blue sapphires may also be diffusion treated, though this treatment is more common for star sapphires. Beryllium treatment is now being used to produce stunning orange and red colors that were once rarely seen. All sapphire treatments should be fully disclosed by any reputable dealer.Sapphire gemology Species: Corundum Color: Blue, colorless, pink, orange, yellow, green, purple, black Chemical composition: Al2O3, Aluminum Oxide Crystal system: (Trigonal), doubly pointy, barrel-shaped, hexagonal pyramids, tabloid shaped Hardness: 9 (Mohs scale) SerpentineSerpentine is the name used for several different aggregate structures which are usually green, yellowish green, or brownish green in color. The finer serpentine is cut as cabochons for gemstones, orcarved into decorative objects. Though serpentine is sometimes confused with jade, serpentine is usually spotted or veined.The serpentine group includes as many as 20 different members. All the serpentines are a basic magnesium silicate, with many containing iron as well. Other elements may also be present in small quantities, including chromium, nickel and cobalt.Two basic structures for serpentine are usually distinguished -- antigorite (leafy serpentine) and chrysotile (fibrous serpentine). The chrysotile minerals are more likely to form serpentine asbestos, while antigorite forms cryptocrystalline masses sometimes with a lamellar or micaceous character. Since asbestos fibers are a health hazard only the antigorite form is used fMost serpentine are opaque to translucent, with a hardness rating ranging from 2.5 to 5.5. Antigorite tends to be the harder variety.Serpentine is fairly light, with
a density of 2.44 to 2.62, slightly lower than quartz. Luster ranges from greasy to waxy to silky. Serpentine is known to be susceptible to acids.Serpentine varieties are found in many places in the world, including Afghanistan, Burma, China, New Zealand, the USA, Canada, UK, Greece, Italy and Norway. Sillimanite Gemstones Sillimanite is an aluminum silicate, related to bothandalusite and kyanite. In fact these three minerals arepolymorphs -- they share the same chemical composition but different crystal structures.Kyanite is formed in a lower temperature/higher pressure environment, while andalusiteforms in lower temperature/lower pressure conditions and sillimanite under higher temperatures/higher pressures.Sillimanite is named after the American chemist Benjamin Silliman (1779-1864). Silliman was one of the first American professors of science and taught at Yale University. He was originally trained as a lawyer and taught law at Yale. The president of the university proposed that Silliman study chemistry and natural history and assume a new professorship in the sciences at Yale. Silliman became an important chemist and geologist and discovered the constituent elements of many minerals. He was also the very first person to distill petroleum.Sillimanite occurs in a number of colors, ranging from colorless to gray-white, yellowish, brownish and bluish. Sillimanite is rarely transparent. Sillimanite also occurs in a fibrous form sometimes known asfibrolite, so named because the mineral appears like a bunch of fibres twisted together. Some of these fibrous sillimanite display chatoyancy or the cat's eye effect, often in an attractive violet-brown shade.Historically, sillimanite has been a rare gemstone, known mainly to collectors. Deposits have been found in Burma, Sri Lanka, Kenya and the USA. Recent finds in India have made sillimanite more widely available, though it is still classified as a collector's gem.
Gemologically, sillimanite has a hardness of 6.5 to 7.5 on the Mohs scale with a vitreous pearly luster. It has a refractive index of 1.655 to 1.684, approximately the same as spodumene. Its specific gravity is 3.23-3.27, placing it between apatite and diopside on the density scale. Like diamond, topaz and fluorite, sillimanite has perfect cleavage.
Spinel Spinel is a special gemstone in many ways. For centuries it was mistaken forruby and gained undeserved fame. Today fine red spinel is more rare than rubybut less valuable. That looks like a delayed revenge for its questionable past. Its name derivation is also ambiguous. Experts are undecided whether it derives from the Greek word for "spark" or the Latin "thorn". Although commonly thought of as red, spinel can be found in a range of beautiful pastel shades. These outstanding shades of pink, purple, orange, blue, plus every combination in between make spinels some of the most desirable stones in the world. Due to its excellent hardness (8 on Mohs scale) and high clarity spinel is a very fine gem for jewelry of all kinds. Spinel is never treated in any way and continues to be a great substitute for ruby and sapphire as well.The coloring agents in spinel are iron, chromium, vanadium and cobalt. Within the spinel group some trade names have become common: Flame spinel: Bright orange to orange-red spinel Balas spinel: Pale red spinel Pleonaste: Dark green to blackish, opaque spinel Hercynite: Dark green to black spinel Grahnite: Blue, violet, or dark green to blackish spinel Gahnospinel: Blue to dark blue or green spinel Picotite: Brownish, dark green, or blackish spinelSpinel occurs with ruby and sapphire mainly in important deposits found in Cambodia, Myanmar, Sri Lanka and Thailand. Other locations are in Afghanistan, Australia, Brazil, Madagascar, Nepal, Nigeria, Tadzhikistan, Tanzania and the United States.Spinel gemology Species: Spinel Color: Red, orange, yellow, brown, blue violet, purple, green, black Chemical composition: MgAl2O4 magnesium aluminum oxide Crystal system: (Cubic) octahedron, twins, rhombic dodecahedron
Hardness: 8 (Mohs scale) Strawberry QuartzQuartz with red inclusions of iron oxide is more rarely found, and is often sold under the name strawberry quartz or "red fire" quartz. Some specimens have very fine inclusions, only visible under magnification, lending the quartz a more or less uniformly strawberry color. Others have clearly visible inclusions and may appear as clear quartz with reddish needles, flakes or spangles.
Strawberry quartz gets its color from inclusions of various forms of iron oxide. There are four different but chemically related iron oxides that may be found in quartz. They include lepidocrocite (FeO(OH)), goethite (also FeO(OH) but with a different crystal structure), limonite (FeO(OH)*nH2O) and hematite (Fe2O3).Some material sold as strawberry quartzis synthetic rather than natural; most of it is simply glass. Fruit Quartz is the general trade term for a group of colorful, translucent materials which are individually known by names such as "cherry quartz," "blueberry quartz," "strawberry quartz,"kiwi quartz," "pineapple quartz," and so on.
They are commonly carved into jewelry components such as beads or pendants or into decorative objects. But don't confuse these synthetic products with genuine quartz with natural iron oxide inclusions.Strawberry quartz is most often found in Russia and in neighboring regions such as Kazakhstan, as well as in Brazil. SugiliteSugilite is a rare mineral of fairly recent discovery. It is named after the Japanese geologist, Ken-ichi Sugi, who first identified it in 1944. It has a distinctive purple color and is usually opaque to translucent. Sugilite has sometimes been called purple turquoise although there is no really no connection at all between sugilite and turquoise.Though sugilite was first discovered in 1944, it did not become of interest to the gemstone world until many years later. In 1979 a major deposit of gem-quality sugilite was found in a manganese mine in the Southern Khalahari desert in South Africa. This important deposit yielded several thousand kilograms of
Click here to enlarge photoStrawberry Quartz from Russia
material.In mineralogical terms, sugilite is classified as a cyclosilicate, in the same class as tourmaline, iolite and the beryl group. Sugilite has a very complex chemical composition, it is a Potassium Sodium Lithium Iron Manganese Aluminum Silicate. It is only rarely found as crystals, usually being massive in form. Sugilite has a Mohs hardness of 5.5 to 6.5 and a specific gravity of 2.75-2.80. It has a refractive index of 1.607-1.61 and typically has a vitreous to waxy luster. Not especially hard, sugilite is quite a durable material since it has poorcleavage.
Sugilite gemstone colors include all shades of purple -- from lilac to plum, including hues of magenta, purple and red violet. Sugilite specimens often contain black matrix, and reddish or yellowish blotches, since the mineral sugilite occurs in brownish yellow and pale pink as well as violet and reddish violet. Sugilite cabochons will often be found mixed with chalcedony.
Sugilite deposits are found in Australia, India, Japan, Canada and South Africa.
Like most colored stones, sugilite is valued based on its color. Specimens with a vivid and intense purple are valued most highly. Since many sugilite specimens are multicolored, the attractive patterns and veining will raise the value of a piece. Sugilite is often available in large sizes, with pieces over 10 carats being common. SunstoneSunstone belongs to the plagioclasefeldspar group, and is named for its unusual spangled or glittery appearance. Its proper mineralogical name, however, is aventurine feldspar, named from a type of glass made with copper that was discovered by chance (from the Italian, a ventura). This is one of the rare cases where the name of a natural stone came from its synthetic simulant.Aventurine is the name used for both a type of green quartz and a golden feldspar. Both have a metallic glittery appearance caused by inclusions. The spangled effect is known as aventurescence. Perhaps to avoid confusion, the name sunstone has been adopted in the gem trade for the feldspar, while the name aventurine (or aventurine quartz) is used for the quartz variety.Sunstone is typically a red-brown hue, with a metallic glitter which is caused
by tiny platelets of hematite or goethite. The glitter is usually gold or red, but very occasionally green or blue. We have found both opaque and transparent/translucent specimens in the market. The opaque material is cut as cabochons while the transparent material can be faceted. Some of the cabochons will display a discernible star effect and are sold under the nameStar Sunstone.Sunstone is a sodium calcium aluminum silicate, with a hardness of 6-6.5 on the Mohs scale. It has a density of 2.62-2.65 and a refractive index of 1.525-1548. It has perfect cleavage.Sunstone deposits are found in India, Canada, Madagascar, Norway, Russia and the USA. In 1987 sunstone was named the state mineral of the state of Oregon in the USA. The Oregon sunstone is rather unique in that it is the only sunstone containing copper crystals.Sunstone has been known for many centuries and has been discovered in Viking burial mounds. Sunstone was thought to have magical properties and could be used to invoke the energies associated with the sun. In ancient Greece, it was thought to represent the sun god, bringing life and abundance to those fortunate enough to own it. The native people in Oregon used it for trade and barter. TanzaniteTanzanite was enthusiastically celebrated as "Gemstone of the 20th Century" after its discovery in 1967. It is named after the East African state of Tanzania where its only deposit has been found. The legendary New York jewelers Tiffany & Co were the first to promote tanzanite as a fine gemstone. Tanzanite is a variety of the zoisite species. In good quality the color is ultramarine to sapphire blue. The most popular color is a saturated blue, which shows a purplish hue shimmering around it.
The only known deposit of tanzanite is a five square mile hilltop at Merelani Hills near Ausha, ten miles south of the Kilimanjaro International Airport in Tanzania.Most rough crystals show a large proportion of brownish-yellow tints, which vanish when heated to 752-932 degrees F (400-500 degrees C).Tanzanite gemology Species: Zoisite Color: Sapphire blue, amethyst, violet Chemical composition: Ca2Al3(Sio4)3(OH) calcium aluminum silicate Crystal system: Orthorhombic, multifaceted prisms, mostly striated Hardness: 6.5-7 (Mohs scale)Birthstone for DecemberTopaz
Topaz of any type is a good jewelry stone and it is historically one of the most important gemstones. With its relatively high refractive index and hardness of eight (Mohs scale), with no special sensitivity to chemicals it can be used, with appropriate care (should be protected from hard knocks), in any jewelry application. Topaz comes in many colors, including clear, brown, yellow, orange, red, pink and blue. The blue topaz, with a pale to medium blue color created byirradiation, can be found in very large sizes at affordable prices. The fine golden-yellow variety, known as Imperial Topaz, is relatively scarce. Topaz colors are rarely vivid. The most common color is yellow with a red tint; the most valuable is pink to reddish. The coloring agents are iron and chromium. The name topaz is most probably derived from an island in the Red Sea, "Topazos", today called Zabargad, the ancient source of peridot. In former times all golden-brown and sometimes also green gemstones were called topaz, which caused sufficient confusion such that today real topaz is referred to as precious topaz.Topaz is the birthstone for those who are born in the month of November.Topaz location and deposits Brazil (Minas Gerais) is the most important supplier for topaz. Other deposits are in Afghanistan, Australia, China, Japan, Madagascar, Mexico, Myanmar, Namibia, Nigeria, Pakistan, Russia, Sri Lanka, Ukraine, United States and Zimbabwe. Natural light blue topaz is also found in England (Cornwall), Northern Ireland and Scotland.Common Topaz treatments Blue topaz begins as colorless or very lightly tinted natural topaz crystals, which are then irradiated to change the color to blue and heated to stabilize the change. Neutron bombardment in a nuclear reactor produces the deep slightly greenish or grayish "London Blue", while electron bombardment in a linear accelerator results in the light aqua-like blue known as "Sky Blue". Combinations of both treatments produce the highly saturated "Swiss" and "Electric" blues. If neutron bombardment has been used, there is residual radioactivity, and the gems must be held, up to a year, before they have "cooled" enough to be worn. In general, blue topaz is modestly priced. Due to the expenses of reactor time the London Blue color is short in supply and climbs in value. In early 1998, a new type of enhanced topaz made its appearance, the surface-enhanced topaz, with colors described as blue to greenish-blue or emerald green. The vast majority of pink topazes are heat-treated yellow stones that turn pink.Topaz gemology Species: Topaz Color: Colorless, yellow, orange, red-brown, light to dark blue, pink-red, red,
violet, light green Chemical composition: Al2SiO4(F2OH)2 fluor containing aluminum silicate Crystal system: Orthorhombic, prisms with multi-faceted ends, often eight-sided in cross-sections along length Hardness: 8 (Mohs scale) TourmalineOne of the most versatile of gemstones, tourmaline is available in every color, from colorless to black. You can find every tone from pastel to dark, and even with one or more colors appearing in the same stone. It truly is a wondrous and fascinating stone!Known for centuries, tourmaline first gained popularity when the Dutch began to import it in the early 17th century from Sri Lanka . They gave the gem a Sinhalese name, Turamali, which is believed to mean stone with mixed colors.Tourmaline is actually the name of a group of related mineral species. In gemological practice, individual species names are not used. Instead, all are simply termed tourmaline. Tourmaline commonly comes from Tanzania, Madagascar, Brazil, Australia, Sri Lanka, the U.S., and Russia, plus other Color is the major characteristic for tourmaline. This stone is found in morehues, shades and nuances than any other gem. Here are some of the most common varieties that are recognized in the gem trade.Rubellite – Varying in color from mid to deep reds resembling ruby, rubellite is one of the rarest and most valuable tourmalines. Many gems in the 17th century Russian Crown jewels, originally thought to be rubies, are actually rubellite tourmalines.Indicolite – From bright blue hues to bluish green colors, indicolite tourmaline is another rare tourmaline color, and high quality specimens are regarded as quite collectable.Chrome – Chrome tourmaline is green, but is considered different from the regular greens as it derives it rich green color from trace elements of chromium. Found in East Africa , chrome tourmaline is rare and is usually found only in smaller sizes.Bi-Color – Variations, zones and color bands in tourmaline are often purposefully accented with the cutting style to show bands and color zones in the gem. Occurring in uncountable colors variations, these are often seen in long acicular crystals. Watermelon – Bi-color tourmalines which show a green skin and a red core; these are sometimes cut as slicesCanary – Bright yellow tourmaline from Malawi .Paraíba – A rare blue-green tourmaline containing copper, Paraiba
tourmalinecan be found in amazing bright neon hues and can command thousands of dollars per carat. Found in a single area in Paraiba, Brazil, it is generally found in comparatively small sizes for tourmaline. Recent finds of copper content tourmaline in Nigeria and Mozambique have also produced similar bright neon tourmaline.Cat's Eye – Chatoyant tourmaline in a variety of colors. It is often found in a rich green.Color-Change – Changes from green in daylight to red in incandescent light.Other varieties may be simply sold with a color prefix, as in pink tourmaline. Like most gems, you want the color to be as intense as possible, however, not too dark or too light.Tourmaline has strong pleochroism , which means you can see different colors or depths of color when viewed at different angles, such as when you rotate the stone in the light.Tourmaline GemologyColor: Colorless, pink, brown, red, yellow, green, blue, black, violet, multi-coloredMoh's Harness: 7-7½ ZirconZircon is known since the Middle Ages. The oldest known zircons are from Western Australia, with an age of 4.4 billion years. The name probably comes from the Persian word "zargun" which means "gold-colored," although zirconcomes in a wide range of different colors. The most popular zircon-color is blue. Zircon is a birthstone for those who are born in December.Colorless when pure, the zirconium silicate takes on various shades due to impurities. The most popular zircon-color is blue. Most blue gemstones come in a pastel blue, but some exceptional gems have a bright blue color. Zircon is also available in green, dark red, violet, yellow, brown, and orange. The brown varieties, mostly found in Southeast Asia, are heat treated in order to produce colorless and blue zircons. In the gemstone trade some terms refer to different colored zircons: Hyacinth: yellow, yellow-red to red-brown zircon Jargon: straw-yellow to almost colorless zircon Starlight: rich, slightly greenish blue zircon variety, created by heatingZircon location and deposits Zircon deposits are mainly alluvial. Zircon is found in Australia, Brazil, Cambodia, Korea, Madagascar, Mozambique, Myanmar, Nigeria, Sri Lanka, Tanzania, Thailand and Vietnam.Common Zircon treatments The brown varieties, mostly found in Southeast Asia, are heat treated at temperatures of 800-1000 degrees C (1472-1832 degrees F), in order to produce
colorless and blue zircons. These colors aren't necessarily stable. Ultraviolet rays or sunlight can produce changes.Zircon gemology Species: Zircon Color: Colorless, yellow, brown, orange, red violet, blue, green Chemical composition: ZrSiO4 zirconium silicate Crystal system: (Tetragonal), short, stocky, four-sided prisms with pyramidal ends Hardness: 6.5-7.5 (Mohs scale)
