Diamond Calculator
Diamond 3D Book
Educational Programs
Testing Laboratory
Diamond Cut Study
Introduction
Recent achievements
Building of cut grading system
Work with scanned diamond models
Example with tilted table
BLResponses
Analysis of illumination
GIA's illumination model
"Brill" software analyses light response
WLR metric and brilliance
Example with mirrors
An observer model
Understanding of brilliance
Practical value of the cut grading system
Acknowledgment
References
 
 
 

1. Introduction
2. Recent achievements
3. Building of cut grading system
4. Work with scanned diamond models
5. Example with tilted table
6. BLResponses
7. Analysis of illumination
8. GIA's illumination model
9. "Brill" software analyses light response
10. WLR metric and brilliance
11. Example with mirrors
12. An observer model
13. Understanding of brilliance
14. Practical value of the cut grading system
15. Acknowledgment
16. References

 
 
  This document has some interactive hyperlinks to additional text [,] and figures [] as well as some interactive modelling software. We recommend you use these hyperlinks and to work on your own in order to better understand the ideas stated. We are sure you will enjoy playing with this software and you will better understand the article as well.

Two software packages is used here for interactive demonstrations:

- Brill software [] operates as a component of your web browser (Internet Explorer is only supported). It will be installed automatically when you enter the interactive page.

- GemAdviser [] operates as standalone application. You need to download and install GemAdviser, if you wish to be able to see GemAdviser photo-realistic models.

 
  Introduction  
  This article is devoted to the study of diamond cut. Application of computer modeling technologies to studying diamond cut and developing a cut grading technique is demonstrated. To build an effective cut grading system one must not only model correctly the diamond under study, but also the illumination and the observer. Conditions of observing white and colored rays in light passed through a diamond are analyzed. The diamond is considered as an object that produces inhomogeneities in the spatial distribution of light. We also discuss how to proceed from analyzing model diamonds to grading the cut of real stones .

The article is directed to specialists on cut issues rather than a guide to consumers in the process of buying a diamond right now. It contains some considerations about the future practical value of a cut study grading system being developed.

We use a language such as facets, prisms, ray paths, mirrors, reflections, and so on. This language is useful for understanding and explaining various phenomena, and many researches uses this language when analyzing and quantitatively describing different phenomena in relation of diamond appearance.

In posting this material we wish to bring attention to the importance of understanding appropriate illuminating and viewing conditions, and we aim to stimulate collaboration toward a standardization of observation conditions for evaluation of diamond appearance.

 
  Recent achievements  
 

If it's time to learn how to grade diamond cut and how to distinguish between good and bad diamonds (from the viewpoint of their cut quality), we can suggest an appropriate method (technology, approach). At the initial stage of our research we have studied of appearance of ideal symmetry diamond models:

The Results of Diamond Cut Studies Carried out in MSU, 1999

and at the second stage we have posted our approach to nonsymmetrical diamonds in September 2000:

Developing of Diamond Cut Grading System by MSU (OctoNus and GC MSU) Computer Tools

Important events regarding our approach have occurred since that time.

A. OctoNus have developed software allowing you to visually analyze the appearance of a diamond and to quantitatively estimate some features of its cut, such as Light Return, Light Leakage, Fish Eye and Contrast, based on a diamond 3D model.

B. Sarin Technologies have developed a method to build a 'solid' 3D model of a scanned diamond. Many users worldwide are now able to create models of real stones and exchange these models via Internet.

C. OctoNus software enables the Sarin 3D model to be 'viewed' and tested without the diamond being present.

D. As a result of these developments it is now possible to develop a system for grading the quality of diamond cut of any individually scanned diamond using 'basic light responses' (BLR) of the diamond in conjunction with formalized criteria established by experts. This means an expert cut quality assessment system is now feasible that could be applied to any diamond irrespective of its shape or symmetry.

 
  Authors :  
 

Sergey Sivovolenko, OctoNus, Moscow, Russia
Yuri Shelementiev, Gemological Center MSU, Moscow, Russia
Vladimir Onischuk, OctoNus, Moscow, Russia
Garry Holloway, Precious Metals, Melbourne, Australia

 
 

For correspondence: serg@next.msu.ru

 
© 2002 Sergey Sivovolenko, Yuri Shelementiev, Vladimir Onischuk, Garry Holloway