DiamCalc : Appraisers
GIA system appraiser

This document shows what criteria DiamCalc uses for diamond grading according to GIA system

The data listed here is not an official GIA 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
Parameter name Meaning E-VG G F
UpAngle Crown angle 34 - 35 32 - 36 30 - 37
DownHeight_GIA % Pavilion depth 43 - 43.5 42 - 44 41 - 46
GirdleHeight_mm Girdle thickness Medium -
Slightly thick
Thin -
Thick
Very thin -
Very thick
Table % Table diameter 53 - 60 52 - 64 51 - 70
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
Culet_mm Culet size Pointed - Medium Pointed -
Slightly large
Pointed - Large
GirdleDeviation % Ratio of max/min diameters -2 - +2 -2 - +2 -2 - +2

GirdleHeight_mm, mm (translation table for girdle thickness)
Girdle description Values
Extremely thin less than 0.08
Very thin 0.08 - 0.12
Thin 0.12 - 0.15
Medium 0.15 - 0.20
Thick 0.20 - 0.33
Very thick 0.33 - 0.40
Extremely thick more than 0.40

Culet_mm, mm (translation table for culet size)
Culet description Values
Pointed less than 0.010
Very small 0.010 - 0.020
Small 0.020 - 0.030
Medium 0.030 - 0.090
Slightly large 0.090 - 0.220
Large 0.220 - 0.400
Very large 0.400 - 0.800
Extremely large more than 0.800

Detailed description of DiamCalc appraisers

HRD system appraiser
AGA system appraiser