This document shows what criteria DiamCalc uses for diamond grading according to AGA system
The data listed here is not an official AGA data. It is provided
here for possibility to check its suitability for your purposes.
OctoNus software recommends that you check the data and modify
it as necessary as described here
before using DiamCalc to grade diamonds for commercial purposes.
Brilliant Cut, 0.50ct or more |
Parameter name |
Meaning |
1A |
1B |
2A |
2B |
Table % |
Table diameter |
53.0 - 58.0 |
52.0 - 60.0 |
51.5 - 63.0 |
51.0 - 64.0 |
UpAngle ° |
Crown angle |
34.3 - 34.7 |
34.0 - 35.0 |
32.1 - 35.8 |
31.6 - 36.4 |
UpHeight_GIA % |
Crown height |
14.3 - 16.3 |
13.5 - 16.8 |
11.6 - 17.9 |
11.1 - 18.1 |
DownHeight_GIA % |
Pavilion depth |
42.8 - 43.2 |
42.5 - 43.5 |
42.0 - 44.0 |
41.5 - 44.9 |
FullHeight % |
Full height |
58.7 - 62.3 |
58.3 - 63.0 |
57.9 - 63.5 |
57.5 - 63.8 |
GirdleRatio |
Ratio of max/min diameters |
0.98 - 1.02 |
0.98 - 1.02 |
0.98 - 1.02 |
0.98 - 1.02 |
Pavilion % |
N/A |
10 - 25 |
10 - 25 |
10 - 25 |
10 - 25 |
GirdleHeight_GIA |
Girdle thickness |
Medium - Medium |
Slightly thin- Slightly thick |
Thin - Slightly thick |
Thin - Thick |
GirdleDeviation % |
Ratio of max/min diameters |
-2 - +2 |
-2 - +2 |
-2 - +2 |
-2 -+2 |
Culet_mm |
Culet size |
Pointed - Pointed |
Pointed - Very small |
Pointed - Small |
Pointed - Medium |
Parameter name |
Meaning |
3A |
3B |
4A |
Table % |
Table diameter |
50.5 - 67.0 |
50.0 - 70.0 |
49.0 - 72.0 |
UpAngle ° |
Crown angle |
30.1 - 37.9 |
29.6 - 39.4 |
29.0 - 40.5 |
UpHeight_GIA % |
Crown height |
9.6 - 19.3 |
8.5 - 20.5 |
7.8 - 21.8 |
DownHeight_GIA % |
Pavilion depth |
41.0 - 45.5 |
40.5 - 46.0 |
38.0 - 48.0 |
FullHeight % |
Full height |
57.0 - 64.1 |
56.5 - 65.0 |
55.0 - 67.0 |
GirdleRatio |
Ratio of max/min diameters |
0.98 - 1.02 |
0.98 - 1.02 |
0.98 - 1.02 |
Pavilion % |
N/A |
10 - 25 |
10 - 25 |
10 - 25 |
GirdleHeight_GIA |
Girdle thickness |
Very thin - Very thick |
Very thin - Very thick |
Extremely thin - Extremely thick |
GirdleDeviation % |
Ratio of max/min diameters |
-2 + 2 |
-2 - +2 |
-2 - +2 |
Culet_mm |
Culet size |
Pointed - Slightly large |
Pointed - Large |
Pointed - Very large |
* All that does not fit 4A group is included in 4B. |
AGA appraiser tables and translation tables:
|