What is DiamCalc and who benefits from it
What is new in the DiamCalc?
High Dynamic Range Demo movies
Caustic Movies in the next versions of DiamCalc
Scenarios - Demo files demonstraite different possibilities and effects of the program
Press Release DiamCalc 3.0 and DiamCalc 3.0 Pro launched by OctoNus
Diamond 3DBook free full version on-line
Video Tutorial - Using DiamCalc & GEM Adviser
DiamCalc Internal Cuts
External cuts (DLL)
Versions history
System requirements
Information for Mac users
Online Store
Illustrated reports
Download DiamCalc
DiamCalc 3.2 beta Documentation (PDF)
External Cuts gallery (Dll)
Online Store
Complete guide
Quick guide on Key operations (How to..)
OctoNus spread & AGS spread
Cut parameters
Cut Quality Estimation
How to Create High dynamic range (HDR) panorama
3DCalc Pro

3DCalc family
DiBox 2.0
GemAdviser Free Version
Helium IG
Helium Polish
Helium Rough
Helium Tender
M-Box 2.0
M-Box 1.5
Oxygen DZ
Oxygen HIG
Oxygen Immersion
Oxygen Inclusion
Oxygen Microscope Server
Oxygen Viewer Free Version
Oxygen XRay Server
Pacor Client
Stereo Viewer Free Version

PACOR - Advanced Computer technologies for Processing of Rough diamonds
Laser Mapping of Concavities
Scanning major and minor symmetry features
Technology patent "A method and apparatus for locating inclusions in a diamond stone"
Immersion Glass
DiamCalc Help : Cut Parameters
OctoNus spread & AGS spread

OctoNus spread

Spread is a parameter that shows the difference between weight of a given diamond and weight of the standard diamond. The standard diamond has the same area as the given diamond but the standard diamond has Tolkowsky proportions with the medium girdle thickness. The spread parameter tells if your diamond looks more or less massive than it really is.

Tolkowsky proportions

Weight 1,00 ct
Diameter 6,47 mm
Sec.diameter 6,47 mm
Total depth 4,00 mm
Crown height (bzl) 16,2 %
Crown angle 34,5
Table diameter 53,0 %
Pavilion depth (mains)43,1 %
Pavilion angle (max)40,75 %
Culet pointed
Girdle (valley)Ex. Thin
Square deviation0,0 %
Star facets39,7 %
Lower facet depth82,0 %
Lower facet length80,5 %
Girdle (valley) 1,0 %
Girdle (bazel) 2,6 %
Girdle offcet0,0 %
Girdle offcet azimuth 0,0 %
Fish eye 10,31 %
Kozibe 6,11 %
Spread 0,00 ct (0 %)
AGS spread -0,1 %

The spread parameter also works with fancy shapes comparing them with round standard diamond.

AGS spread

AGS Spread (ct) = (D / 6.47)3 - C

AGS Spread (%) = (1 - C * (6.47 / D)3) * 100%

C - weight of diamond (ct)
D - diameter of diamond (mm)
6.47 - diameter in mm of diamond with weight 1 ct and Tolkowsky proportions


Total height
Crown height (bezel)
Crown height (valley)
Crown angle
Table diameter
Pavilion depth (mains)
Pavilion angle
Girdle valley
Square deviation
Star facets
Lower facets
Girdle (valley)
Girdle (bezel)
Fish eye
Advanced 2
Crown angle (min)
Crown angle (max)
Crown angle (avg)
Pavilion angle (min)
Pavilion angle (max)
Pavilion angle (avg)
OctoNus Spread & AGS Spread

Helium Polish cut parameters