660 GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019
A fter the discovery of a gem mineral with un-usual color-change behavior in the RussianUral Mountains during the early 1830s,
Swedish mineralogist Nils Adolf Erik Nordenskiöldnamed this new gem alexandrite in 1834 in honor ofthe future Czar Alexander II (Kozlov, 2005). This im-mediately created a royal and romantic aura aroundthis variety of chrysoberyl. The most coveted alexan-drites exhibit a lush green to greenish blue color indaylight and a warm, bright red shade in candlelight(Levine, 2008); some fine Brazilian and Indian alexan-drite examples are shown in figures 1–3 and 6. Thisphenomenal color change is caused by the presenceof trace Cr3+ substituting for Al3+ in the chrysoberylcrystal structure. Alexandrite is routinely describedas “emerald by day, ruby by night.” It is a stone ofduality—green or red, cool or warm, day or night(Levine, 2008). Because of its rare and attractivecolor-change phenomenon, alexandrite has beenhighly sought after and is one of the most valuablegemstones in the trade.
Alexandrite, particularly fine-quality material, isalso very scarce; it has generally been a byproduct of
mining other major colored stones. Overall produc-tion statistics are hard to evaluate. It has been minedin Russia (Kozlov, 2005; Schmetzer, 2010), Tanzania
(Gübelin, 1976; Schmetzer and Malsy, 2011b) andZimbabwe (Brown and Kelly, 1984; Schmetzer et al.,2011) as a byproduct of emerald mining, and inBrazil (Proctor, 1988; Cassedanne and Roditi, 1993;Voynick, 1988) and India (Newlay and Pashine,1993; Patnaik and Nayak, 1993; Panjikar and Ram - chan dran,1997; Voynick, 1988; Valentini, 1998) alongwith cat’s-eye and nonphenomenal chryso beryl, as
GEOGRAPHIC ORIGIN DETERMINATIONOF ALEXANDRITEZiyin Sun, Aaron C. Palke, Jonathan Muyal, Dino DeGhionno, and Shane F. McClure
FEATURE ARTICLES
The gem and jewelry trade has come to place increasing importance on the geographic origin of alexandrite, asit can have a significant impact on value. Alexandrites from Russia and Brazil are usually more highly valuedthan those from other countries. In 2016, GIA began researching geographic origin of alexandrite with theintent of offering origin determination as a laboratory service. Unfortunately, collecting reliable samples withknown provenance can be very difficult. Alexandrite is often recovered as a byproduct of mining for other gem-stones (e.g., emerald and corundum), so it can be difficult to secure reliable parcels of samples because pro-duction is typically erratic and unpredictable. The reference materials studied here were examined thoroughlyfor their trace element chemistry profiles, characteristic color-change ranges under daylight-equivalent and in-candescent illumination, and inclusion scenes. The data obtained so far allow us to accurately determine geo-graphic origin for alexandrites from Russia, Brazil, Sri Lanka, Tanzania, and India. Future work may help todifferentiate alexandrites from other localities.
In Brief • Geographic origin can significantly affect alexandrite’svalue.
• Collecting reliable alexandrite samples with knownprovenance can be very difficult because production istypically erratic and unpredictable.
• Trace element chemistry data obtained from LA-ICP-MS are the primary consideration in determining its ge-ographic origin.
• Color-change behavior and inclusions are used assecondary factors to support the geographic origindetermination.
well as other pegmatitic minerals. In Sri Lanka(Zwaan, 1982; Zoysa, 1987, 2014), it is mined as abyproduct of corundum, cat’s-eye and nonphenome-nal chryso beryl, and other minerals. The supply ofalexandrite in the U.S. market has been low since the1990s, as the supplies from the initial rush in Brazilpresumably started drying up (Costanza, 1998). How-ever, demand for the gemstone has stayed high in theU.S., especially for large stones with high clarity andintense and distinctive color change (again, see fig-ures 1–3 and 6). The situation has changed somewhat
recently, with new production from Sri Lanka, Brazil,and Tanzania (Jarrett, 2015).
With the development of these modern sourcesand the subsequent rapid changes in the alexandritesupply chain, there is growing demand from the gemtrade for geographic origin determination for finealexandrite. Origin is increasingly important, as it isoften used as a factor in establishing a stone’s value.Stones from Russia or Brazil can easily command ahigher price than alexandrite from Tanzania and Zim-babwe with the same attributes. Because of all of
GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019 661
Figure 1. A group of rings featuring alexandrite from Brazil. Top row, left to right: A three-stone alexandrite ringwith a 1.35 ct center oval flanked by two smaller ovals with a combined weight of 1.29 carats and a ring with a1.32 ct kite-shaped center stone flanked by two kite-shaped diamonds weighing a total of 0.32 carats. Bottom row,left to right: Rings featuring a 1.71 ct oval and a 0.72 ct cushion-cut alexandrite. The designs also feature melee-cutalexandrites of unknown provenance and diamonds. The image on the left was photographed in daylight-equiva-lent lighting, the image on the right in incandescent light. Detailed procedures for photographing the alexandritesshown in this article are provided in appendixes 2 and 3, online at https://www.gia.edu/doc/WN19-Alexandrite-Appendixes2-3.pdf. Photos by Robert Weldon/GIA; courtesy of Omi Privé.
Figure 2. This ring features a 0.72 ct Brazilian cushion-cut alexandrite with a strong color-change effect, and thedesign uses additional alexandrite melee and diamonds as accents. The loose oval alexandrite below the ringweighs 4.13 ct and hails from India. The image on the left was photographed in daylight-equivalent lighting, theimage on the right in incandescent light. Photos by Robert Weldon/GIA; courtesy of Omi Privé.
these market factors, in 2016 GIA initiated a researchproject centered around alexandrite geographic origindetermination. Since then, many samples have gonethrough the laboratories and had their characteristicchemistry, colors, and inclusions carefully docu-mented. Reference stones with reliable provenancewere obtained from multiple sources. The data col-lected on stones from a single country from varioussources were generally found to be self-consistent,which corroborates the validity of the origin determi-nation criteria developed. GIA announced the origindetermination service in early 2019 and will continueto develop its alexandrite database to ensure the mostaccurate identification and origin reporting for thejewelry trade.
ALEXANDRITE GEOGRAPHIC LOCALITIES: A BRIEF SUMMARY
Russia. The original locality for alexandrite remainsone of the most highly valued sources (Kozlov, 2005;Schmetzer, 2010). Alexandrites from Russia are gen-erally a byproduct of emerald mining from metamor-phic mica-schist veins in ultramafic host rocks. Themicaceous rocks are called “glimmerites” because ofthe glowing sheen of the micas.
Russian production began in the 1830s but wanedin the twentieth century when mining emphasisshifted to beryllium, and it lapsed with the fall of theSoviet Union in 1991. Recent efforts have been un-dertaken to increase Russian alexandrite production.
There are a few important deposits: Mariinskoye(Malyshevskoye); Cheremshanskoye; Sretenskoye(Sverdlovskoye), where the first Russian emeraldswere discovered; Krasnobolotnoye, where the largestand most beautiful Russian alexandrites were foundin 1839; and Krasnoarmeiskoye. Of these, the Mari-inskoye deposit has historically had the largest min-ing operation.
Sri Lanka. Sri Lanka is one of the world’s most im-portant gemstone localities (Zwaan, 1982; Zoysa,1987, 2014). The main gem-bearing areas are the Rat-napura district in Sabaragamuwa Province, Elaherain Central Province, Okkampitiya in Uva Province,and the Kataragama area in Southern Province. Thechrysoberyl occurrences are more frequently foundin and around Morawaka and Deniyaya in SouthernProvince. All of these gems occur in alluvial depositsunderlain by Precambrian metamorphic rocks, andtheir original source remains unknown. There waslittle reliable information available on the amountand value of the gem material recovered in Sri Lankauntil 1923, when the discovery of fine-qualityalexandrites in Ratnapura’s Pelmadulla deposits wasreported. There was a constant supply of Sri Lankanalexandrite in the market until the end of the 1980s,when production dropped (Proctor, 1988).
Most Sri Lankan alexandrites have a weaker colorchange than Russian and Brazilian stones (see theloose stones in figure 4), although finer-quality ma-terial can show color change from saturated green to
662 GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019
Figure 3. This matched pair of cat’s-eye alexandrites from Brazil exhibits double phenomena (color change andchatoyancy) and weighs a total of 2.43 carats. The design also features alexandrite and diamond melee accents.The image on the left was photographed with daylight-equivalent lighting and the image on the right with incan-descent light. Pinpoint light was used to reveal the stones’ chatoyancy. Photos by Robert Weldon/GIA; courtesyof Omi Privé.
red. However, Sri Lankan alexandrites often achievelarge sizes with high clarity, and stones up to 600 cthave been examined by GIA.
Brazil. In the 1980s, as Russia’s Uralian deposits wereproducing little and supplies from Sri Lanka weredrying up, the pegmatite district in Minas Gerais,Brazil, became for a time the world’s major alexan-drite producer (Koivula, 1987a,b; Proctor, 1988;Cassedanne and Roditi, 1993).
From 1846 until the 1980s, the Americana andSantana Valleys, near the city of Padre Paraíso in theTeófilo Otoni–Marambaia pegmatite districts, ac-counted for approximately 95% of the chrysoberyland cat’s-eye chrysoberyl found in Minas Gerais. Butfine alexandrites from the Americana, Santana, Gil,and Barro Preto Valleys were rare. Brazil’s foremostsource of fine alexandrite was the Malacacheta re-gion in the northeast of Minas Gerais State. Alexan-drite was mined there from 1975 to 1988, with peakproduction in the early 1980s. In 1987, the Lavra deHematita alexandrite deposit was discovered. Thismarked the greatest discovery of Brazilian alexan-drite. To date, Hematita has yielded tens of kilos ofalexandrite that are generally larger and cleaner thanthose from Malacacheta, including some facetedgems weighing up to 30 ct that exhibit extraordinarycolor change. A few locations in the adjacent statesof Bahia and Espírito Santo also produce alexandrite,albeit with an overall lower quality in terms of color,clarity, size, or some combination.
Most of the finest cyclical twinned alexandritemineral specimens in today’s market come fromBrazil (see figure 5). Brazilian alexandrites have adistinct color change that is often comparable tothat of the finest Russian stones (see figure 6), butwith a higher clarity, larger size, and much greateravailability. Brazil also produces some of the world’sfinest cat’s-eye alexandrite, such as the pair in figure3 that exhibit a distinct color change and a sharpeye.
India. In the religions associated with Southeast Asiaand the Indian subcontinent—Hinduism, Jainism,and Buddhism—cat’s-eye chrysoberyl holds a place ofdistinction among the Navratnas (a combination ofnine sacred gemstones) (Brunel, 1972). Chrysoberylhas been mined in five Indian states—Kerala, MadhyaPradesh, Odisha (formerly Orissa), Andhra Pradesh,and Tamil Nadu—since the 1980s and ’90s. Alexan-drite is found there either in pegmatites intrudinggranitic rock or in biotite schists developed along thecontact zone of pegmatites and peridotites (Somanand Nair, 1985; Patnaik and Nayak, 1993; Newlayand Pashine, 1993; Panjikar and Ramchandran, 1997;Valentini, 1998).
Indian alexandrites usually have a weaker colorchange than Russian and Brazilian material (see thering mounted with a heart-shaped stone in figure 4).However, stones with good color change and clarityare comparable to the finest Russian and Brazilianspecimens. The 4.13 ct loose oval in figure 2, repre-
GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019 663
Figure 4. The ring on the far left features a heart-shaped alexandrite from India. The second ring is mounted withan oval-shaped alexandrite—possibly from Madagascar—and melee-cut diamonds. All loose faceted stones arefrom Sri Lanka. The stones range from 4.01 to 22.99 ct. The image on the left was taken under an LED light sourcesimulating daylight-equivalent lighting, while the right-hand image was taken under an LED light source simulat-ing incandescent illumination. Photos by Kevin Schumacher; courtesy of LC Gem Collection Inc.
senting top-quality Indian alexandrite, exhibited sat-urated blue-green color under daylight and saturatedred under incandescent light. Many small Indiancat’s-eye alexandrites with weak color change arefairly common in today’s market, but Indian cat’s-eye alexandrite with distinct color change and sharpeyes are rare.
Tanzania. Alexandrite has come mainly from twomining areas in Tanzania: Lake Manyara in thenorth and Tunduru in the south (Gübelin, 1976;Johnson and Koivula, 1996, 1997; Henricus, 2001;Schmetzer and Malsy, 2011b; Jarrett, 2015). LakeManyara is a primary deposit where alexandrite hasbeen found in a phlogopite-bearing schist. Alexan-drite from Tunduru has been mined from a second-ary alluvial deposit. Alexandrite from Lake Man yara(figure 7) entered the market in the 1960s, with sig-nificant production into the early 1980s. Johnsonand Koivula reported a wide variety of gem materi-
als, including alexandrite, from Tunduru at the Tuc-son show in 1996. Since then, the area has beenknown for producing large quantities of alexandrite,and material from Tunduru was available in theU.S. market in 2015 according to Michael Couch ofMichael Couch & Associates (Jarrett, 2015). In theearly 2000s, emerald and alexandrite were reportedfrom Mayoka, just outside Manyara National Park,by Abe Suleman, a director of the InternationalColored Gemstone Association and a member ofthe Tanzania Mineral Dealers Association (Henri-cus, 2001), but environmental concerns stoppedmining activities in late 2000 and little materialwas produced.
A chameleon brooch mounted with beautifulrough alexandrite crystals from Lake Manyara on itsback and small faceted alexandrites on its legs andtail changes from blue green to violet when viewingunder daylight and incandescent light, as seen in fig-ure 7.
664 GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019
Figure 5. A cyclical twinned Brazilian alexandrite mineral specimen, 4.13 cm in the longest dimension, shows dis-tinct color change from green to red under daylight-equivalent lighting and incandescent illumination, respec-tively. The image on the left was taken under an LED light source simulating daylight-equivalent lighting, whilethe image on the right was taken under an LED light source simulating incandescent illumination. Photos byKevin Schumacher; courtesy of John I. Koivula.
Minor Alexandrite Geographic Localities.Zimbabwe.Alexandrite has been recovered from the Novello de-posit of Zimbabwe’s Masvingo district (Schmetzer,2011). It is located in a phlogopite-bearing host rock
with surrounding serpentinite. Peak production wasin the 1960s and 1970s and yielded larger, mostly non-facet-grade material. The material is considered verydark and only suitable for faceting small stones with
GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019 665
Figure 6. A suite of fine Brazilian alexandrite exhibiting the finest color change seen in this material. The leftimage was taken under an LED light source simulating daylight-equivalent lighting, while the right photo wastaken under an LED light source simulating incandescent illumination. Photos by Robert Weldon/GIA; courtesyof Evan Caplan.
Figure 7. Rough and faceted alexandrite from Lake Manyara, Tanzania. The left image was taken under an LEDlight source simulating daylight-equivalent lighting, while the right photo was taken under an LED light sourcesimulating incandescent illumination. Photos by Robert Weldon/GIA; courtesy of Omi Privé.
intense color change. The deposit is believed to stillproduce alexandrite.
Madagascar. Alexandrite originating from phlogo-pite-bearing host rocks comes from primary emeralddeposits in the Mananjary region of Madagascar(Schmetzer and Malsy, 2011a). The other deposit, inthe Ilakaka region (Hänni, 1999; Milisenda et al.,2001), is a secondary deposit where different vari-eties of chrysoberyl—including alexandrite—havebeen found. Occasionally, large alexandrite crystalsof gem quality have been recovered in the LakeAlaotra region.
Myanmar. In Myanmar (formerly Burma), the peg-matites in the western part of the Mogok Valley inSakangyi or Barnardmyo, and the alluvial placers inthe Mogok Stone Tract near Mogok, Kyatpyin, andBarnardmyo, have produced gem-quality alexandrite(“Alexandrite world occurrences...,” n.d.). Burmesealexandrites usually fluoresce intense red under long-and short-wave UV radiation due to lack of iron.
Australia. Dowerin is the first recorded alexandriteoccurrence in Western Australia, known since 1930.The deposit has yielded many small crystals (Bevanand Downes, 1997; Downes and Bevan, 2002).
United States. In recent years, small chrysoberylcrystals with weak color change were reported froma mine at La Madera Mountain in Rio Arriba County,New Mexico (“Alexandrite world occurrences &mining localities,” n.d.).
Zambia. Some Zambian alexandrite with similarcharacteristics to Zimbabwean stones has appearedin the market. No reliable information is currentlyavailable.
MATERIALS AND METHODSReference Samples. GIA’s research project on alexan-drite origin started in early 2016, with suites ofalexandrites from both Russia and Brazil. Almost allRussian material came from Warren Boyd, who ac-quired them as a mining consultant at the Malyshevaemerald and alexandrite mine from 1992 to 2007.There are four different sources for the Brazilianalexandrites. Seventeen specimens came from EvanCaplan, who acquired them from a source directlyconnected to a mine owner in Brazil. Fifteen of the
Brazilian gems came from Nilam Alawdeen, wholater provided three Sri Lankan and two Indian stonesduring this project. Spectrum Fine Jewelry & ExoticGems supplied 140 Brazilian alexandrites. Four addi-tional samples came from the GIA Museum. It isvery likely that all the Brazilian material came fromthe Hematita deposit in Minas Gerais.
A few months later, eight Sri Lankan, twenty-oneTanzanian, and two Indian alexandrites were pro-vided to the lab by LC Gem Collection Inc., a SriLanka–based gem company. Gem dealer ChandikaThambugala submitted nine Sri Lankan stones to thelab. The GIA Museum was also able to provide thir-teen Sri Lankan, four Indian, and five Tanzaniangems. In some cases, all that was known about a spec-imen was the country of origin; specific mines wereunknown. However, the Tanzanian stones were verylikely from Lake Manyara. An additional 18 Indianstones were provided by Lance Davidson. Fieldgemologist Vincent Pardieu provided us with somestones from his personal collection: three Madagascaralexandrites bought in Madagascar; nine Zambianstones bought in Mahesak, Thailand, from a trust-worthy source; and one Burmese sample purchasedfrom the trade in Mogok. Five Zimbabwean stonescame from two different sources: Two were borrowedfrom the personal collection of Yusuke Katsurada, asenior gemologist and scientist in GIA’s Tokyo labo-ratory, and the GIA Museum provided the otherthree. Detailed reference sample provenance is listedin appendix 1, table 1, online at https://www.gia.edu/doc/WN19-Alexandrite-Appendix1.pdf.
Procedures for Alexandrite Identification in GIA Lab-oratories. When an alexandrite first arrives at theGIA laboratory, we ask a question even more funda-mental than geographic origin: Is this a naturalalexandrite? Fourier-transform infrared spectroscopy(FTIR) is performed on every alexandrite to distin-guish natural from synthetic material (Stockton andKane, 1988) and to identify imitations. Naturalalexandrites are then sent for laser ablation–induc-tively coupled plasma–mass spectrometry (LA-ICP-MS); see Groat et al. (2019), pp. 512–535 of this issue.This method is used to acquire trace element chem-istry for geographic origin determination, if originservice is requested by the client.
After advanced analysis, the stone is given to apreliminary gemologist for standard gemologicaltesting and identification. The stone is examinedunder a standard GIA desktop microscope for inclu-
666 GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019
sions that would be indicative of a natural or syn-thetic origin. Photomicrographs are taken andRaman spectroscopy is performed if there are crys-talline inclusions that might aid in origin determi-nation (see Groat et al., 2019, pp. 512–535 of thisissue). The colors exhibited by the alexandrite arealso considered as possible evidence of origin. Astone’s warm and cool colors are also recorded inGIA’s database with careful photographic documen-tation under standardized conditions (see below). Thestone is then sent to a more senior gemologist to fur-ther check all the physical and chemical propertiesto confirm the stone’s identity and complete theidentification and origin determination.
Photography.GIA Digital Imaging for Color-ChangeStones. GIA has a set of standardized procedures forphotographing color-change stones to ensure consis-tency in appearance reproduction. The image of analexandrite is captured using a variety of high-qualitycameras and lenses in a specially made light box pro-duced by the GIA instrument department. An LEDlight with a color temperature around 6500 K is usedas a daylight-equivalent light source, while an LEDlight with a color temperature around 2700 K is usedas an incandescent light source. The final printed im-ages are viewed in a controlled lighting environmentand compared to the actual stone. Slight color adjust-ments are made with Adobe Photoshop software ifneeded, using a monitor that is maintained and colorcalibrated using GretagMacbeth calibration software.
Photomicrography of Inclusions. Photomicrographsare taken using various Nikon microscopes, includ-ing an Eclipse LV100, SMZ1500, and SMZ10 (Renfro,2015a,b). Photographs of the inclusion scenes are cap-tured using Nikon DS-Ri2 digital cameras. Variouslighting environments including darkfield, bright-field, and fiber-optic illumination are used to high-light specific internal features. Image stacking(Renfro, 2015a) is sometimes employed to maximizethe depth of field of an image.
Raman Spectroscopy. Raman spectra are collectedwith a Renishaw inVia Raman microscope system.The Raman spectra of the inclusions are collectedusing a Stellar-REN Modu Ar-ion laser producinghighly polarized light at 514 nm at a nominal resolu-tion of 3 cm–1 in the 2000–200 cm–1 range. Each in-clusion spectrum is accumulated three times at 20×or 50× magnification. In many cases, the confocal ca-
pabilities of the Raman system allow inclusions be-neath the surface to be analyzed.
FTIR. Fourier-transform infrared spectra are col-lected using a Thermo Fisher Nicolet 6700 FTIRspectrometer equipped with an XT-KBr beam splitterand a mercury-cadmium-telluride (MCT) detectoroperating with a 4× beam condenser accessory. Thebeam is transmitted through the stone. The spectraare collected at a nominal resolution of 4 cm–1 with1.928 cm–1 data spacing. Each stone is scanned 128times to achieve a high signal-to-noise ratio.
LA-ICP-MS. Trace element chemistry is acquiredusing a Thermo Fisher iCAP Qc ICP-MS coupledwith an Elemental Scientific Lasers NWR213 laserablation system. It incorporates a Nd:YAG laser rodthat emits light with a wavelength of 1064 nm in theinfrared and a frequency quintupler system to gener-ate a 213 nm (1/5 of 1064 nm) ultraviolet wavelengththat is used to ablate samples. Ablation is achievedusing a 55 μm diameter circular spot size, a fluence(energy density) of approximately 10 J/cm2, and a 20Hz repetition rate. National Institute of Standardsand Technology (NIST) Standard Reference Material(SRM) 610 (http://georem.mpch-mainz.gwdg.de/sample_query.asp; Jochum et al., 2005) is used as anexternal standard. 27Al is used as an internal stan-dard, with a value of 425000 calculated and roundedfrom pure chrysoberyl. A similar method was usedin works done by Malsy and Schmetzer (Schmetzer,2010; Schmetzer and Malsy, 2011b; Schmetzer et al.,2011).
RESULTS AND DISCUSSIONTrace Element Chemistry of Alexandrite from Dif-ferent Countries. In general, trace element chemistryis the most important factor in determining a geo-graphic origin for alexandrite. By carefully examiningour reference datasets, we concluded that Mg, Fe, Ga,Ge, and Sn are the five best discriminators to distin-guish different geographic locations (figure 8). B, V,and Cr were also good discriminators for separatingalexandrites among some countries (see figures 9 and10), but must be considered as an addition to the firstfive with specific criteria. The generalized trace ele-ment profiles are listed in table 1. The results de-scribed herein and shown in figures 8–10 aregenerally consistent with the results previously re-ported by Malsy and Schmetzer.
Using any two of the five discriminators (Mg, Fe,
GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019 667
668 GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019
Figure 8. Plots of Mg,Fe, Ga, Ge, and Sn con-centration in alexan-drite reference stonesfrom different coun-tries. Ten plots weregenerated by plottingany two elementsagainst each other. Theorigin of most alexan-drite samples can beconfidently ascertainedusing these 10 plots.
Ga
(ppm
w)
TRACE ELEMENT DISCRIMINATION
Sn (ppmw)0.1 1 10 1000100
Mg
(ppm
w)
Ga (ppmw)40 400
Fe (
ppm
w)
Sn (ppmw)0.1 1 10 1000100
Ga
(ppm
w)
Fe (ppmw)600 6000
Ga
(ppm
w)
Ge (ppmw)0.1 1 10 100
Mg
(ppm
w)
Fe (ppmw)600 6000
Fe (
ppm
w)
Ge (ppmw)0.1 1 10 100
Ge
(ppm
w)
Sn (ppmw)0.1 1 10 100 1000
Sn (
ppm
w)
Mg (ppmw)1 10 100 1000
Ge
(ppm
w)
Mg (ppmw)1 10 100 1000
1
100
10
1000
40
400
600
6000
40
400
600
6000
0.1
10
1
100
0.1
100
1000
1
10
0.1
10
1
100
40
400
1
1000
100
10
Tanzania (n=27)
Myanmar (n=1)
Sri Lanka (n=33)
Zimbabwe (n=5)
Russia (n=43)
India (n=27)
Zambia (n=9)
Brazil (n=176)
Madagascar (n=3)
Ga, Ge, and Sn) to plot against each other, 10 plots canbe generated (figure 8). Alexandrites from differentcountries have their own characteristic chemistry.
Mg—Indian and Tanzanian alexandrites havehigh Mg concentrations, while Brazilian, Zam-bian, and Zimbabwean stones have low Mg con-centration. Russian and Sri Lankan stones havewide ranges of Mg concentrations that overlapwith every other source.
Fe—Zambian and Zimbabwean stones have rela-tively high Fe concentration, while Tanzanian,Brazilian, and Sri Lankan specimens have mediumFe concentration. Russian and Indian stones havethe lowest Fe concentrations.
Ga—Sri Lankan stones have the highest galliumconcentration. Indian, Russian, Zambian, and Zim-
babwean material falls in a middle range, whileTanzanian and Brazilian alexandrites have the low-est Ga concentrations.
Ge—Russian alexandrites have the highest germa-nium concentrations, while Sri Lankan, Indian,Brazilian, and Tanzanian stones have the lowest.Zambian and Zimbabwean stones have mediumGe concentrations.
Sn—Russian, Brazilian, Zambian, and Zimbab-wean alexandrites have higher Sn concentrations,while Indian specimens have lower amounts. SriLankan and Tanzanian stones have similar Snconcentrations in the middle range.
In addition to these five discriminators, B, V, andCr are very useful for some specific cases. Thesethree elements can further validate geographic origin
GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019 669
Figure 9. Boron can beused to separate SriLankan alexandritefrom Indian, Zambian,and Zimbabwean sam-ples. Some Brazilianstones have the lowestboron concentrationsamong all countries.
Tanzania (n=27)
Myanmar (n=1)
Sri Lanka (n=33)
Zimbabwe (n=5)
Russia (n=43)
India (n=27)
Zambia (n=9)
Brazil (n=176)
Madagascar (n=3)
B (
ppm
w)
BORON AS A TRACE ELEMENT DISCRIMINATOR
Cr (ppmw)
10 100 1000 10000
0.5
5
50
500All reference Sri Lankanalexandrites have boronconcentration above 20 ppmw.
Indian, Zambian, and Zimbabweanalexandrites have boron concentrationbetween 2.5 and 20 ppmw.
Some Brazilian alexandrites havevery low boron concentrationbelow 2.5 ppmw.
conclusions (figures 9 and 10). Boron can be used todistinguish Sri Lankan alexandrite from Indian, Zam-bian, Zimbabwean, and some of the low-boronBrazilian stones (figure 9). According to our referencedatabase, all Sri Lankan alexandrites collected so farhave boron concentrations above 20 ppmw, while al-most all Indian, Zambian, and Zimbabwean alexan-drites have boron concentrations between 2.5 and 20ppmw, and some Brazilian alexandrites have the low-est boron concentrations, below 2.5 ppmw (figure 9).Besides boron, the chromophores vanadium andchromium are also very important in separating In-dian, Zambian, and Zimbabwean alexandrites frommaterial from other localities (figure 10). Accordingto our reference database, some Sri Lankan and allIndian alexandrites have the highest V/Cr ratioamong all reference stones (indicated by the blackoval in the top left of the plot in figure 10). Zambianand Zimbabwean alexandrites have the lowest V/Crratio among all reference stones (indicated by theblack oval in the bottom right of the plot in figure10).
Selective Plotting for Alexandrite Geographic OriginDetermination. We have found that the use of the“selective plotting” method can greatly enhance theaccuracy of origin determination for alexandrite (fig-ure 11). The method essentially involves plotting
data for the unknown client stone only against refer-ence data with similar full trace element profiles; seePalke et al. (2019), pp. 536–579 of this issue. In thismethod, discrete “windows” are selectively createdaround the trace element data of the client stone, andonly reference data within these windows are plottedwhile everything else is filtered out. This results inplots that are much easier to read and accurately in-terpret. A few examples are shown in figure 11. Theplots after discrimination usually point to simple anddefinite results.
Characteristic Color Change of Alexandrite fromDifferent Countries. Anyone who is familiar withalexandrite is well aware that material from differentcountries has different characteristic color-changebehaviors. Many dealers have a good sense of wherea specimen comes from through visual observationunder daylight and incandescent lighting conditions.After examining hundreds of alexandrites, we canprovide some examples of typical color-change pair-ings of alexandrite from different countries (figure12). The images are from stones submitted to GIA atthe five different global identification laboratories;each origin was confirmed by analyzing their traceelement profiles as measured by LA-ICP-MS. Whilethere is usually a range in the warm/cool color pairsseen for alexandrite from a single locality, each local-
670 GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019
Figure 10. Cr-V and V-B plots prove very useful in validating the origin of Indian, Zambian, and Zimbabweanalexandrites. The Indian stones, along with some of the Sri Lankan specimens, have the highest V/Cr ratios. TheZambian and Zimbabwean stones have the lowest V/Cr ratios.
V (
ppm
w)
Cr VS. V AND V VS. B TRACE ELEMENT DISCRIMINATION
Cr (ppmw) V (ppmw)
10
10
100
1000
10000100 1000
B (
ppm
w)
0.5
10
50
5
500
100 1000
Some Sri Lankan and Indian alexandriteshave higher V and lower Cr.
Zambian and Zimbabwean alexandriteshave lower V and higher Cr.
Tanzania (n=27)
Myanmar (n=1)
Sri Lanka (n=33)
Zimbabwe (n=5)
Russia (n=43) India (n=27)
Zambia (n=9)
Brazil (n=176) Madagascar (n=3)
GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019 671
TABLE 1. Generalized trace element profiles of alexandrite samples in ppmw.
15.5–208
45.0
31.4
4.47–3140
93.0
26.1
21.5–347
102
84.0
156–14200
3090
1640
1390–8610
2780
2480
171–406
263
255
1.08–76.4
10.3
4.55
37.9–1550
324
244
Range
Average
Median
Russia
*bdl = below the detection limit of the LA-ICP-MS analysis
672 GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019
Figure 11. The left col-umn shows Sn-Mg plotsbefore discriminationfor alexandrite from(top to bottom) SriLanka, Brazil, Russia,Tanzania, and India.The right columnshows the same Sn-Mgplots after applicationof the selective plottingmethod. This methodleaves in reference datathat are similar to un-known stones and fil-ters out irrelevantinformation, makingthese plots much easierto interpret accurately.
Sn (p
pmw
)Sn VS. Mg TRACE ELEMENT DISCRIMINATION
Mg (ppmw)
Sn (p
pmw
)
Mg (ppmw)
Sn (p
pmw
)
Mg (ppmw)
Sn (p
pmw
)
Mg (ppmw)
Sn (p
pmw
)
Mg (ppmw)
Sn (p
pmw
)
Mg (ppmw)
Sn (p
pmw
)
Mg (ppmw)
Sn (p
pmw
)
Mg (ppmw)
Sn (p
pmw
)
Mg (ppmw)
Sn (p
pmw
)
Mg (ppmw)
Tanzania (n=27)
Myanmar (n=1)
Sri Lanka (n=33)
Zimbabwe (n=5)
Russia (n=43)
India (n=27)
Zambia (n=9)
Brazil (n=176)
Madagascar (n=3)
1 100 100010
1 100 100010
1
1 1 100 1000
1 10 100 1000 1 10 100 1000
10
100
1
1000
10
1010 100 1000
100 100010
0.1
100
10
1000
1
0.1
10
1
100
1000
0.1
1
10
100
1000
0.1
100
10
1
1000
0.1
1000
100
10
1
0.1
100
1000
10
1
0.1
100
1
10
1000
0.1
100
1000
1
10
0.1
10
1
100
1 10 1000100
1 1000100
1
0.1
10
10 100 1000
ity does tend to have its own specific range, and thedifferent colors seen are generally helpful in narrow-ing down the origin. The color types for each countryin figure 12 were determined based on both colori-metric analyses of the images and visual observa-tions by gemologists.
Sri Lankan alexandrites usually have a yellowishgreen component in daylight-equivalent lighting anda brownish or orangy component with incandescentillumination. Brazilian alexandrites tend to have abluish green component in daylight-equivalent light-ing and a reddish purple to purple component underincandescent light. The color-change characteristicsof alexandrites from other countries are not as wellknown, because of the limits of our current imagedatabase.
Geographic origin determinations should neverbe based on color alone; trace element chemistry isthe primary factor in establishing origin. However,color can support the origin determination derivedfrom trace element chemistry. The authors groupedall types of alexandrite color-change pairings into thefollowing general categories (corresponding to typesin figure 12):
1. Sri Lanka – Cool Even though Sri Lankan alexandrites typically
have brownish to grayish overtones, some lackthese overtones and fall into the Cool category.In lighter-toned stones, hue changes from greenor bluish green in daylight to purplish red orgrayish purple in incandescent light. Saturationis low to medium in fine-quality stones, with amedium to dark tone.
2. Sri Lanka – Warm Specimens in the Warm category exhibit the
typical brownish to grayish overtones thatcharacterize many Sri Lankan alexandrites.Daylight hues are generally yellowish com-pared to other alexandrites, ranging from yel-lowish green to brownish yellow to theoccasional pure green. In incandescent light,they usually appear brownish, with yellowishbrown, orangy brown, brownish pink, brown-ish purple, brownish yellow, and brownish redhues. Saturation is generally low to medium,with medium to dark tones.
3. Brazil Top Brazilian stones are generally considered to
exhibit the finest color change of any alexan-drites. Most tend to have a bluish component
to their daylight color. Their hues are greenishblue to blue-green to pure green in daylight andred-purple to purple in incandescent light.These colors are often vivid, with medium tohigh saturation and medium to dark tone.
4. Russia Russian alexandrite can exhibit some of the
finest colors in top-quality material. Hues aregenerally pure green to bluish green to green-blue in daylight and purple-red to purple in in-candescent light. Stones tend to have mediumto high saturation, with medium to dark tone.
5. Tanzania Tanzanian alexandrite is capable of producing
superb color change. Hue tends to range frombluish green to greenish blue in daylight andred-purple to purple in incandescent light. Tan-zanian stones typically have medium to highsaturation and medium to dark tone.
6. India Hue for Indian alexandrite tends to range from
green to bluish green in daylight, changing topurplish violet, purple, brownish purple, or red-purple in incandescent light. Indian stones typ-ically have low to medium saturation andmedium to dark tone.
Inclusions in Alexandrite from Different Countries.Geological environment not only controls the pres-ence of certain trace elements and their concentra-tion but also impacts the inclusions an alexandritecontains. GIA has captured photomicrographs of in-clusions in alexandrite and is using them to supportthe origin determinations made by chemistry andcolor.
Brazil. Metal sulfides have frequently been found inBrazilian alexandrites (figure 13A and B) and are al-most diagnostic for this origin in the authors’ opin-ion, although alabandite, a metal sulfide with similarappearance to the inclusions in figure 13A and B, wasreported by Gübelin and Koivula (1986) in a non-color-change Sri Lankan chrysoberyl. Minute parti-cles sometimes group together to form fingerprints(figure 13C) and wispy clouds (figure 13D). Crystalsof fluorite (figure 13E) and mica crystals and flakes(possibly phlogopite or biotite, figure 13F) are also ob-served occasionally. Other researchers have also re-ported fluorite, phlogo pite, and biotite and
GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019 673
674 GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019
Figure 12. Characteris-tic color-change pairingsof alexandrite from dif-ferent countries. Thephotos were selectedfrom GIA’s digital imag-ing database of produc-tion stones, which weretaken using GIA digitalimaging procedures andprinted on GIA alexan-drite reports.
Sri Lanka – CoolDaylight Incandescent Daylight Incandescent
additionally calcite, apatite, albite, and two-phaseand multiphase fluid inclusions in Brazilian alexan-drites (Gübelin and Koivula, 1986; Proctor, 1988;Koivula and Kammerling, 1988).
Sri Lanka. Sri Lankan stones submitted to GIA areusually clean, but the identification team has stilldocumented many inclusions. Strong brown colorzoning has only been observed in Sri Lankan stonesand may be diagnostic of this origin (figure 14A), al-though additional observations are needed to confirmthis. Under fiber-optic illumination, these browncolor zones are populated with reflective milkyclouds (figure 14B). Very rarely, elongate prismaticsillimanite crystals (figure 14C) and euhedral feldsparcrystals (figure 14D) have been observed. Fingerprints(figure 14E and F) formed by two-phase and multi-phase fluid inclusions are normal. Minute particles
may group together to form flake-like clouds (figure14G). Occasionally, tubes with brownish oxide stains(figure 14H) can also be observed. Additionally, greenmica, quartz crystals, and slender rod-like crystals ofcolumbite, spessartine, ilmenite, and alabandite havepreviously been observed in Sri Lankan alexandritesand non-color-change chryso beryls (Gübelin andKoivula, 1986).
Russia. In our limited observations of inclusions inRussian alexandrite, phlogopite mica has been seenforming flattened, rounded, unevenly shaped crystals(figure 15A) and clusters of cotton-like inclusions(figure 15B). Very rarely, corroded and rounded fluo-rite crystals (figure 15C) and prismatic rod-like tour-maline crystals (figure 15D) have been observed. Bothinclusions were first reported in Russian alexan-drites. Tourmaline crystals, chemically identified as
GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019 675
Figure 13. Inclusions inBrazilian alexandrite. A:A metal sulfide crystal in-clusion surrounded by amelted/decrepitated halounder diffused fiber-opticillumination. B: Chalco -pyrite crystal surroundedby melted/decrepitatedhalo under darkfield andoblique fiber-optic illumi-nation. C: Silk, bands,and fingerprints composedof minute particles underoblique fiber-optic illumi-nation. D: Clouds/finger-prints composed ofminute particles underdarkfield and obliquefiber-optic illumination. E: Rounded fluorite crys-tal inclusions under dif-fused illumination. F:Mica crystals under dark-field illumination. Fieldsof view: 1.99 mm (A), 1.42mm (B), 2.34 mm (C), 7.19mm (D), 0.55 mm (E), and2.00 mm (F). Photomicro-graphs by Jonathan Muyal(A, C), Tyler Smith (B, D,E), and Makoto Miura (F).
A B
C D
E F
dravite by LA-ICP-MS (Sun et al., 2019), may be di-agnostic of the origin, although additional observa-tions are needed to confirm this. Sometimes it is notdifficult to see pseudo-hexagonal growth sectionsshown in different colors under brightfield illumina-tion between crossed polarizers (figure 15E). Graphitefilm, resembling a spaceship in figure 15F, has beenoccasionally observed in Russian material. Roundedcotton-like clouds composed of tiny particles (figure15G) show unique texture and may be diagnostic.
Planes of fluid inclusions (figure 15H) have also beenobserved. Further work is underway to collect addi-tional information on reliably sourced Russianalexandrite. Mica (e.g., phlogopite and biotite) andamphibole inclusions are most commonly observedin Russian alexandrites (Gübelin and Koivula, 1986).
Tanzania. For alexandrite from Tanzania, inclusionsof actinolite crystals, mica, monazite, xenotime, androunded metamict zircon have been observed (Gübe-
676 GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019
Figure 14. Inclusions inSri Lankan alexandrite.A: Brown color zoningand strong parallel grain-ing under brightfield illu-mination. B: The samebrown color zoning in (A)becomes milky bandsunder darkfield andoblique fiber-optic illumi-nation. C: Well-formedprismatic sillimanitecrystals under darkfieldand oblique fiber-optic il-lumination. D: Euhedralfeldspar crystal under dif-fused illumination. E:Fingerprints formed byparallel lines of fluidsand tiny crystals underdarkfield and diffusedfiber-optic illumination.F: Irregularly shaped crys-tals and fingerprints com-posed of two-phase andmultiphase fluid inclu-sions under darkfield illu-mination. G: Flake-likecloud of particles underoblique fiber-optic illumi-nation. H: Tubes withbrownish oxide stainsunder diffused fiber-opticillumination. Fields ofview: 7.19 mm (A), 7.19mm (B), 2.90 mm (C),1.99 mm (D), 2.90 mm(E), 3.57 mm (F), 1.44 mm(G), and 1.99 mm (H).Photomicrographs byTyler Smith (A–D) andJonathan Muyal (E–H).
A B
C D
E F
G H
lin and Koivula, 1986). Currently, there are only afew images of crystals and fingerprint-like inclusionsin GIA’s production database. Groups of prismatic ap-atite crystals (figure 16A, B, and C) and nests of finesilk (figure 16D) have been observed in one Tanzan-ian alexandrite.
India. Fingerprint-like inclusions in Indian alexan-drite are usually composed of tiny needles and ovaland round reflective particles (figure 17A, B, and C).
This feature may be diagnostic of the origin, al-though additional observations are needed to confirmthis. Occasionally, zircon crystals (figure 17D) withtension fissures have been observed. Figure 17Eshows two adjacent crystals with unknown identity;the larger one shows a metallic luster. Groups ofelongate negative crystals (figure 17F) are also ob-served sometimes in Indian alexandrite. Addition-ally, mica flakes (biotite, muscovite, etc.) are oftenobserved (Panjikar and Ramchandran, 1997). Quartz
GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019 677
Figure 15. Inclusions inRussian alexandrite. A:Rounded, unevenlyshaped flat transparentphlogopite crystals underdarkfield illumination. B: A dense cluster of col-orless, bladed phlogopitecrystals breaks the sur-face of the stone underdarkfield and obliquefiber-optic illumination.C: Corroded and roundedfluorite crystals underdiffused illumination. D: Prismatic rod-liketourmaline crystalsunder brightfield illumi-nation between crossedpolarizers. E: Pseudo-hexagonal growth sec-tions shown in differentcolors under brightfieldillumination betweencrossed polarizers. F:Graphite film underdarkfield illumination.G: Rounded cotton-likeclouds under obliquefiber-optic illumination.H: Minute two-phase andmultiphase fluid finger-prints under diffused illu-mination. Fields of view:0.80 mm (A), 1.99 mm(B), 1.26 mm (C), 1.44mm (D), 3.57 mm (E),0.72 mm (F), 4.79 mm(G), and 1.44 mm (H).Photomicrographs byMakoto Miura (A), TylerSmith (B), and JonathanMuyal (C–H).
A B
C D
E F
G H
and apatite crystals (Patnaik and Nayak, 1993) aresometimes randomly scattered or in isolation. Nee-dles of rutile and colorless sillimanite can also be ob-served (Panjikar and Ramchandran, 1997).
Other Localities. GIA lacks inclusion information onalexandrite from Madagascar, Zimbabwe, Zambia,and Myanmar. The field gemology team is activelyworking to expand GIA’s reference collection forthese stones.
CONCLUSIONS Determining alexandrite’s geographic origin is a com-plicated process that requires careful examination ofa wide range of physical and chemical properties. Inorder to make a final determination, we evaluate acombination of the three most important character-istics: trace element chemistry, color-change behaviorunder daylight-equivalent lighting and incandescentillumination, and inclusions. Of these three charac-teristics, trace element chemistry obtained from LA-ICP-MS is the primary consideration. Color andinclusions are used as secondary factors to supportthe origin determination derived from trace elementchemistry.
The trace elements Mg, Fe, Ga, Ge, and Sn are thefive best discriminators to distinguish alexandritefrom the major producing countries of Russia (figure18), Sri Lanka, Brazil, India, and Tanzania. B, V, andCr are good discriminators for separating alexandrites
among some countries, but they must be consideredas a complement to the first five trace elements withspecific criteria, rather than on their own.
Most Sri Lankan alexandrites have a yellowishgreen component in daylight-equivalent lighting anda brownish or orangy component in incandescent il-lumination. Brazilian alexandrites have a bluishgreen component in daylight-equivalent lighting anda purple to purplish red component in incandescentillumination. The color characteristics of alexan-drites from other sources are less well known at themoment, but this remains an area of active research.
Sulfides with metallic luster may be diagnosticinclusions for Brazilian alexandrites. Prismatic rod-like tourmaline crystals and rounded cotton-likeclouds composed of tiny particles may be diagnosticfor Russian alexandrites. Fingerprint-like inclusionscomposed of tiny needles and oval and round reflec-tive particles may be unique to Indian alexandrites.Strong brown color zoning is a good indication of SriLankan origin. Characterization of inclusion scenesin alexandrite from the various localities is an activearea of research in this project, and future work mayhelp identify additional microscopic indicators of astone’s origin.
Alexandrite origin is an ongoing project for theGIA research and identification department. One ofthe largest efforts on this front is to add samples ob-tained by GIA’s field gemology team to our referencedatabase. It can be difficult to find reliable alexandritesamples from secondary deposits such as Sri Lanka,
678 GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019
A B
C D
Figure 16. Inclusions inTanzanian alexandrite. A:Prismatic apatite crystalwith slightly rounded edgesand uneven termination. B:Large colorless apatite crys-tal on the left and smaller,slightly tapered phlogopitecrystal on the right. C: Apa -tite crystal with faint nee-dles and particles. D: Nestof fine silk and smallplatelets. The “X” is an ar-tifact from the facet junc-tions. Fields of view: 1.99mm (A), 1.76 mm (B), 1.76mm (C), and 2.90 mm (D).Photomicrographs by TylerSmith; oblique fiber-opticand darkfield illumination.
Tunduru in Tanzania, or Ilakaka in Madagascar. Thatis why our reference data were obtained from trustedmembers of the trade or the GIA Museum. As this
new origin service evolves, future efforts of the fieldgemology team will focus on obtaining samples fromthese sources as material becomes available. Addi-
GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019 679
A B
C D
E F
Figure 18. Russian alexandrite in daylight-equivalent light (left) and incandescent light (right). The twinned crys-tal from Malysheva measures 32.35 mm, and the faceted stone weighs 2.61 ct. Photos by Robert Weldon/GIA;courtesy of William Larson.
Figure 17. Inclusions inIndian alexandrite. A:Needles and tiny oval-shaped reflective particlesunder oblique fiber-opticand darkfield illumina-tion. B: Needles and tinyoval reflective particlesunder darkfield illumina-tion. C: Needles, a minuteand large reflective oval,and round particles underdarkfield illumination. D:Zircon crystal inclusionsurrounded by tension fis-sures under darkfield illu-mination. E: Largeunknown crystal withmetallic luster and adja-cent small crystal withhalo-like tension fissureunder darkfield illumina-tion. F: Elongate negativecrystals under diffused il-lumination. Fields ofview: 0.72 mm (A), 1.26mm (B), 2.41 mm (C), 1.26mm (D), 1.44 mm (E), and1.58 mm (F). Photomicro-graphs by Jonathan Muyal(A, B, D, E, F) and MakotoMiura (C).
tionally, the internal crystal growth pattern and mor-phology of rough crystals have been used as factorsfor geographic origin determination by other re-searchers (Schmetzer, 2011; Schmetzer and Malsy,2011a,b). These two areas can enhance our currentmethods and are worth investigating. Third, differentdeposits within a country can contain crystals withvery different morphologies, producing material withvarying trace element chemistries that show differ-ent colors and inclusions. Further work will be
needed to collect additional data on stones from allmajor locations in order to delineate the differences,not only for alexandrite from different geographic lo-cations but also for alexandrite from a single source.In this there is a truth that applies to all gemologicallaboratories, no matter how mature and well estab-lished: We must remain vigilant and continue ex-panding the state of our gemological knowledge if weare to uncover the story of any precious stone thatpasses through our hands.
680 GEOGRAPHIC ORIGIN OF ALEXANDRITE GEMS & GEMOLOGY WINTER 2019
ABOUT THE AUTHORSMr. Sun is a research associate, Dr. Palke is a senior research sci-entist, Mr. Muyal is a former staff gemologist, Mr. DeGhionno issenior manager of colored stone services, and Mr. McClure isglobal director of colored stone services at GIA’s laboratory inCarlsbad, California.
ACKNOWLEDGMENTSThe authors deeply thank Omi Privé for providing high-endalexandrite jewelry and faceted stones for photography. EvanCap lan, John Koivula, and LC Gem Collection Inc. are greatlythanked for providing high-end faceted alexandrite and roughmineral specimens for photography. Warren Boyd, Evan Caplan,Vincent Pardieu, Chandika Thambugala, Nilam Alawdeen, Yusuke
Katsurada, Lance Davidson (Davidson Inc.), LC Gems CollectionInc., and Spectrum Fine Jewelry & Exotic Gems are thanked forproviding alexandrite stones for chemical analysis and taking pho-tomicrographs of inclusions to build our reference database. Weare deeply grateful to Robert Weldon and Kevin Schumacher fortheir alexandrite photos. Robison McMurtry and Diego Sanchezprovided GIA’s digital imaging procedures for color-changestones. Many thanks are owed to Yusuke Katsurada, MakotoMiura, Sudarat Saeseaw, Vararut Weeramonkhonlert, DanielGirma, Tyler Smith, Virginia Schneider, Mei Mei Sit, Sze LingWong, Chun Fai Chow, Nathan D. Renfro, Claire Malaquias, andChristopher M. Breeding for constant support and contributionson sample testing and data collection and the important sugges-tions they provided throughout the project.
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