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Diamond calculator
: Documentation
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AGA system appraiser
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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.
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Brilliant
Cut, 0.50 ct or more
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Parameter
name
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Meaning
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1A
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1B
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2A
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2B
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Table
%
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Table
diameter
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53.0
- 58.0
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52.0
- 60.0
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51.5
- 63.0
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51.0
- 64.0
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UpAngle
°
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Crown
angle
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34.3
- 34.7
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34.0
- 35.0
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32.1
- 35.8
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31.6
- 36.4
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UpHeight_GIA
%
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Crown
height
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14.3
- 16.3
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13.5
- 16.8
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11.6
- 17.9
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11.1
- 18.1
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DownHeight_GIA
%
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Pavilion
depth
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42.8
- 43.2
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42.5
- 43.5
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42.0
- 44.0
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41.5
- 44.9
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FullHeight
%
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Full
height
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58.7
- 62.3
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58.3
- 63.0
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57.9
- 63.5
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57.5
- 63.8
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GirdleRatio
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Ratio
of max/min diameters
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0.98
- 1.02
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0.98
- 1.02
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0.98
- 1.02
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0.98
- 1.02
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Pavilion
%
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N/A
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10
- 25
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10
- 25
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10
- 25
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10
- 25
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GirdleHeight_GIA
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Girdle
thickness
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Medium
- Medium
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Slightly
thin- Slightly thick
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Thin
-
Slightly thick
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Thin
- Thick
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GirdleDeviation
%
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Ratio
of max/min diameters
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-2
- +2
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-2
- +2
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-2
- +2
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-2
-+2
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Culet_mm
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Culet
size
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Pointed
- Pointed
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Pointed
-
Very small
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Pointed
- Small
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Pointed
- Medium
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Parameter
name
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Meaning
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3A
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3B
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4A
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Table
%
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Table
diameter
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50.5
- 67.0
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50.0
- 70.0
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49.0
- 72.0
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UpAngle
°
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Crown
angle
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30.1
- 37.9
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29.6
- 39.4
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29.0
- 40.5
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UpHeight_GIA
%
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Crown
height
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9.6
- 19.3
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8.5
- 20.5
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7.8
- 21.8
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DownHeight_GIA
%
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Pavilion
depth
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41.0
- 45.5
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40.5
- 46.0
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38.0
- 48.0
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FullHeight
%
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Full
height
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57.0
- 64.1
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56.5
- 65.0
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55.0
- 67.0
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GirdleRatio
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Ratio
of max/min diameters
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0.98
- 1.02
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0.98
- 1.02
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0.98
- 1.02
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Pavilion
%
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N/A
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10
- 25
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10
- 25
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10
- 25
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GirdleHeight_GIA
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Girdle
thickness
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Very
thin -
Very thick
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Very
thin -
Very thick
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Extremely
thin - Extremely thick
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GirdleDeviation
%
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Ratio
of max/min diameters
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-2
+ 2
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-2
- +2
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-2
- +2
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| Culet_mm
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Culet
size
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Pointed
-
Slightly large
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Pointed
- Large
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Pointed
- Very large
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*
All that does not fit 4A group is included
in 4B.
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