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|
Diamond Grading
Cut
|
Class |
Grade |
| Excellent |
1 |
0 - 3 |
| Good |
2 |
4 - 5 |
| Fair |
3 |
6 - 7 |
| Poor |
4 |
8 - 9 - 10 |
|
| Too Shallow |
Excellent |
Too Deep |
|
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AGS = American Gem Society
GIA = Gemological
Institue of America
|
IDEAL
PROPORTIONS |
RANGE
OF GENERALLY
ACCEPTABLE PROPORTIONS |
|
53
to 57%
59 to 61%
43 to 43.5%
34 to 35º
40º
14.8 to 15.5%
medium to sl thick |
Table
Diameter
Total Depth
Pavilion Depth
Crown Angle
Pavilion Angle
Crown Height
Girdle |
53.0
to 66.0%
57.0 to 63.0%
41.5 to 45.0%
30.5 to 37.5º
39 to 42º
11 to 16.2%
thin to thick |
|
|
 |
|
| Colorless |
| Stones
in these grades will "face-up" colorless
(i.e., slight traces of color will not
be apparent in mounted stones to other
than the trained eye). |
| Small
stones in this range will "face-up" colorless
when mounted but larger ones will be tinted |
| Mounted
stones in these grades will display a yellowish
tint even to the untrained eyes. |
|
|
|
|
 |
|
| Flawless |
| Inclusions
are difficult to locate or see under 10X. |
| Inclusions
present less difficult to locate or see
under 10X |
| Inclusions
are readily seen at 10X, although they
remain invisible to the unaided eye when
the diamond is viewed face up. |
| Inclusions,
or the effect, can be seen by the unaided
eye |
| Inclusions
are easily visible to the unaided eye. |
| Inclusions
are so obvious and large that they affect
both the brilliancy and beauty of the diamond. |
| Shattered
appearance or vivid disfiguring and dangerous
inclusions and surface marks. |
|
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