|
G.I.A. uses a systematic and comprehensive approach to analyzing
cut using four classes.
They are as follows:
Individual Proportion and Finish Classes
|
Table
|
|
Size
|
Class
|
|
< 51%
|
4
|
|
51-52%
|
3
|
|
53-60%*
|
1
|
|
61-64%
|
2
|
|
65-70%
|
3
|
|
+70%
|
4
|
|
* Up to 62% in stones
under 0.50 ct.
|
|
|
Crown
|
|
Angle
|
Class
|
|
< 30
|
4
|
|
30-32
|
3
|
|
32-34
|
2
|
|
34-35
|
1
|
|
36
|
2
|
|
37
|
3
|
|
> 37
|
4
|
|
|
Pavilion
|
|
Depth
|
Class
|
|
< 41
|
4
|
|
41
|
3
|
|
42
|
2
|
|
43
|
1
|
|
44
|
2
|
|
45-46
|
3
|
|
> 46
|
4
|
|
|
Girdle
|
|
Thickness
|
Class
|
|
extremely
thin
|
4
|
|
very
thin
|
3
|
|
thin
|
2
|
|
medium
|
1
|
|
slightly
thick
|
1
|
|
thick
|
2
|
|
very
thick
|
3
|
|
extremely thick
|
4
|
|
|
Culet
|
|
Size
|
Class
|
|
none
|
1
|
|
small
|
1
|
|
medium
|
1
|
|
slightly large
|
2
|
|
large
|
3
|
|
very large
|
4
|
|
extremely large
|
4
|
|
|
Finish
|
|
Description
|
Class
|
|
excellent
|
1
|
|
very good
|
1
|
|
good
|
2
|
|
fair
|
3
|
|
poor
|
4
|
|
---
|
|
Major
Symmetry
|
|
any major
symmetry
variation
|
4
|
|
|
* Between make classes, there
are differences in value that reflect proportions' effects on appearance
and weight. There are also differences based on the labor cost represented
by finish quality.
|
Class 1:
|
This class of diamonds can cost up to 15%
more than Class II diamonds. These stones are formerly considered
more "ideal" in cutting. |
|
Class 2:
|
Most of the jewelry market centers around
diamonds with these proportions |
|
Class 3:
|
Diamonds having more proportion variations
producing a greater yield weight and trading approximately 5 to 15%
less than comparable Class II stones. |
|
Class 4:
|
Diamonds with proportion variations with obvious effects
on appearance, weight, or durability, potentially trading as much
as 50% lower than Class II stones. |
Back to Cut
|
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Cut -
GIA Cut Classification
