DiamCalc
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3DCalc : Key Operation Quick Guide
HRD system appraiser

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

The data listed here is not an official HRD 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 Very good Good
UpAngle ° Crown angle 30.7 - 37.7 27.0 - 40.6
DownAngle ° Pavilion angle 39.60 - 42.25 38.45 - 43.15
GirdleHeight_GIA Girdle thickness Thin - Medium Thin - Very thick
Table % Table diameter 52.8 - 66.2 50.6 - 70.2
GirdleRatio Ratio of max/min diameters 0.980 - 1.020 0.980 - 1.020
Pavilion % N/A 10 - 25 10 - 25
UpHeight_GIA % Crown height 10.8 - 16.2 8.8 - 18.2
Kozibe ° Kozibe effect 6 - 91 0 - 91
FishEye % FishEye effect 0 - 100 0 - 100
FullHeight % Total height 55.5 - 63.9 53.0 - 66.9
Culet_mm Culet size Pointed - Medium Pointed - Slightly large
GirdleDeviation % Ratio of max/min diameters -2 - +2 -2 - +2
GirdleHeight_GIA, %
(translation table for girdle thickness)
Girdle description Values
Extremely thin less than 0.75
Very thin 0.75 - 1.75
Thin 1.75 - 2.75
Medium 2.75 - 4.75
Thick 4.75 - 6.25
Very thick 6.25 - 7.75
Extremely thick more than 7.75
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

 
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