Diamond Cut Study
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Study of Interdependence:
Fancy-color Diamond Appearance, Cut, and Lighting Conditions
Fancy-Color Diamonds:
Better Color Appearance by Optimizing Cut

1 Content
2 Color optimization method
3 Diamond absorption spectra
4 Two representations of colors
5 A good fancy colored diamond should be bright and saturated
6 Color potential of a colored diamond plate
7 DiamCalc ray tracing options and photorealistic images
8 One spectrum different cuts and different lightings
9 Process flow
10 Exploring rough diamond potential
11 Rough allocation example
12 Different allocation plans
13 Automatic color optimization
14 Optimization by color
15 Optimization by contrast
16 Optimization results
17 Computer-aided color optimization
18 Expert considerations
19 The final stage: expert decision
20 Verification of the technology: CZ material
21 Real photos of CZ stones and photorealistic images based on Helium scanned 3d models
22 Verification on fancy shapes CZ
23 Summary
24 More information about diamond cut study technologies
25 Terms of colorimetry science (Hunt, 2004)
26 Acknowledges
27 References
Computer modeling of gemstones for improvement of their color appearance
Visible adsorption spectra and DiamCalc-files of colored gem materials
3DBook
DiamCalc Internal Cuts gallery
External Cuts gallery (Dll)
Diamond cuts gallery
 
A good fancy colored diamond should be bright and saturated
Munsell color coordinates are converted to xyz in: G. Wyszecki, W. S. Stiles. 2000. Color Science: Concepts and Methods, Quantitative Data and Formulae, 2nd Edition. We have converted xyz to Luv color coordinates according to standard formulae.

A good colored diamond should have both high brightness and saturation. On the Brightness/Saturation diagram of the fixed yellow hue one can see yellow colors of different brightness and saturation. These colors are tending to be near the upper right corner.

The Munsell color chips positions are placed as described before.

While grading diamond fancy color a grader determines the masterstone or color chip closest to the graded diamond. For color calculations it is necessary to draw borderlines between different color grades. First we draw these borderlines in the middle between Munsell color positions.

Then we found that sometimes these borderlines have a little logic and we have changed borderlines positions in a way that better describes the logic of color difference. It is just an idea how the current color grading system can be improved in future.

For different diamond spectra shown before, here there are coordinates of the diamond plates of various thickness having same spectra are plotted on the diagram. Here a question comes: at that thickness the given material will receive a fancy grade?

The middle blue line shows that this material can be fancy colored in very thin plates. The red curve shows bigger range between max and min thickness.

From the one hand, maximum and minimum thickness corresponds with the particular color grade. From the other hand, its corresponds with light path in a cut diamond

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