Diamonds: Beauty and Brawn Carl Wozniak Graduate Gemologist (GIA) Northern Michigan University
Transcript
1. Diamonds: Beauty and Brawn Carl Wozniak Graduate Gemologist
(GIA) Northern Michigan University
2. The allure of diamonds The worlds love of diamonds started
in India. Romans set uncut diamonds in jewelry By the 1400s,
diamonds had become fashionable in Europe. Roman ring, 4 A.D.
3. Why the allure? Diamonds are cherished because: They are
rare They are durable They are beautiful They have value They are
expensive to mine and cut
4. Cutting Diamonds are extremely hard. In order to cut them,
you have to use other diamonds. Rough diamond
5. Diamond anatomy A round brilliant cut diamond has either 57
or 58 facets.
6. What makes diamonds sparkle? A polished diamonds beauty lies
in a complex relationship with the light around it. Facets on the
stone reflect light externally and internally.
7. What makes diamonds sparkle? We see this interplay between
light and the diamond in three qualities Brilliance- the degree to
which light from within the stone returns to our eye Fire- the play
of colors from the refraction of light within the stone
Scintillation- the bits of light that flash as the stone is
moved
8. Brilliance In brilliant stones, much of the light that
enters leaves through the crown. Less brilliant stones result when
light leaks out the pavilion.
9. Fire Fire, also known as dispersion, is the color play
within a diamond caused by refraction of light in the stone.
10. Scintillation Scintillation is caused by light reflecting
off the stones facets.
11. Grading diamonds Why grade diamonds? Diamond grading: Makes
it possible to discuss diamonds simply and concisely; Helps you
compare stones; Helps identify quality.
12. Grading diamonds The 4 Cs Color Clarity Cut Carat
weight
13. Color While there are fancy colored diamonds that can be
extremely expensive, typical diamonds increase in value as they get
closer to colorless. The currently used grading scale was developed
by the Gemological Institute of America A, B, C were not used to
prevent confusion with existing scales. Hope Diamond 45.52 ct.,
VS-1, Fancy deep grayish blue
14. Rule of thumb Colorless face up and face down D, E, F
Colorless face up, nearly colorless face down G, H, I, J Faint
yellow face up, faint yellow face down K, L, M Very light yellow
face up and face down N, O, P, Q, R Light yellow (substantial)
color face up or down S, T, U, V, W, X, Y, Z
15. Color Color is very difficult to judge in mounted stones
Proper lighting is essential
16. Clarity Most diamonds come with some amount of junk inside
them. We call these inclusions. Scratches and other surface
imperfections are called blemishes. Before the 1950s people in the
diamond industry had no way to accurately describe a diamonds
features so that everyone understood them in the same way.
17. Clarity The GIAs diamond grading system was developed in
1953 to give professionals a way to evaluate diamonds and
communicate quality to others.
18. Clarity Five clarity factors that determine the grade of a
diamond Size of inclusion Number of inclusions Position of
inclusions Nature of inclusions Color or relief of inclusions The
clarity grade is not based on the sum of everything in the stone,
but is based on the largest and most visible characteristics.
20. Clarity Grades Flawless (F) stones are exceedingly rare and
never worn. Millenium Star, 203.04 ct., D, Flawless Flawless stones
have no visible inclusions under 10 X magnification, and there are
no blemishes on the stones surface.
21. Clarity Grades Internally Flawless (IF) diamonds have the
potential to become flawless stones. Internally flawless stones
have no visible inclusions under 10 X magnification, but there are
blemishes on the stones surface.
22. Clarity Grades Very Very Slightly (VVS) included diamonds
Contain minute inclusions that are extremely or very difficult for
a skilled grader to see under 10 X. VVS1= extremely difficult to
see face up (one or two pin points) VVS2= somewhat easy to see
23. Clarity Grades Very Slightly (VS) included diamonds Contain
minor inclusions that are difficult to easy for a skilled grader to
see under 10 X. VS1= difficult to see inclusions VS2= somewhat easy
to see Typically small crystals or feathers near the edge.
24. Clarity Grades Slightly Included (SI) diamonds Contain
noticeable inclusions that are easy or very easy for a skilled
grader to see under 10 X. SI1= easy to see inclusions SI2= very
easy to see. Eye visible. Typically crystals, feathers or clouds
centrally located.
25. Clarity Grades Included (I) diamonds Contain obvious
inclusions to a skilled grader under 10 X. I1= quite visible
inclusions I2= easily visible I3= extremely visible. Affects the
stones durability. I-2 I-3
26. Cut Diamonds can be cut in many different shapes, but this
is not all we mean by cut. Cut refers to not only the shape of the
diamonds, but its proportions and finish, factors which determine
the sparkle of the diamond.
27. Cut Round brilliant cut diamonds have been studied the
most. They are the most common The proportions are relatively
consistent
28. Cut
29. Cut Misalignment of facets, misshapen facets, and pointing
problems go hand-in- hand. Where you find one, youll usually find
the others.
30. Carat weight Diamonds weight is measured in carats. 1 ct. =
1/5 gm. 1/100 ct. = 1 point
31. Carat weight Rule of Thumb 1 All other things being equal,
the bigger the stone, the more expensive it is.
32. Carat weight Rule of Thumb 2 Cost jumps dramatically at
magic sizes.
33. The care and feeding of diamonds Diamonds have a high
affinity for grease. Rough diamonds are actually sorted using
grease tables. Grease changes the refractive index of the stone,
causing light to leak out the pavilion.
34. The care and feeding of diamonds Use an old toothbrush and
soapy water to clean under the stone. Can also use ultrasound or
steam Keep gold jewelry away from chlorine bleach.
35. Synthetic diamonds Synthetic diamonds are becoming more
common, but they are usually small stones, yellowish stones.
Diamonds are made under temperatures of about 2,200 F and 50,000
atmospheres.
36. Synthetic diamonds Cremated remains can be made into
diamond.
37. Common Diamond Simulants Cubic Zirconium (Zircon Oxide) CZ
has slightly less brilliance or sparkle than a diamond and more
fire or flashes of color CZ also comes in many colors.
38. Common Diamond Simulants Telling CZ from diamond About 75%
heavier than diamond CZ is softer, you see this in abraded facet
junctions Orange pavilion flash Usually flawless Many colors
Thermal conductivity
39. Common Diamond Simulants Moissanite- Silicon carbide Has
inclusions and color differences Similar thermal conductivity Very
hard Slightly lighter than diamond Moissanite has a lot more fire
than diamond.
40. Common Diamond Simulants Moissanite- Silicon carbide But,
moissanite is strongly doubly refractive
41. A little knowledge will make you a better consumer. Youre
invited to clean and examine your own stones.