On grading the symmetry of a round brilliant cut diamond

[Serg]

Dear colleagues,



We have posted an article



On grading the symmetry of a round brilliant cut diamond



(The authors are Sergey Sivovolenko, Yuri Shelementyev, and Garry Holloway).



Please have a look at it:

http://www.cutstudy.com/cut/english/symmetry/index.htm


or



http://www.gemology.ru/cut/english/symmetry/index.htm



The reason why this article was appeared is our understanding of imperfection of current approaches for diamond symmetry grading. We are sure that the future symmetry grading will be based not only on “a feature that can be discovered by loupe” but also on “a feature that can influence on diamond appearance and optic”. We welcome your suggestions. We are sure that the further steps in this direction will be the most efficient if the labs and other specialists from different industry and market segments will combine their efforts and develop a unified system. The open discussion allows to avoid mistakes at the initial stages and to develop a reliable system.



Current diamond industry and market require a reliable symmetry grading system, and this need is growing. Diamond industry development is limited by old diamond grading systems. That is why diamonds can not compete with other luxury products if diamond grading systems will not change in order to allow cutters to create more beautiful diamonds. Current systems prize a diamond that is similar with other “good” diamond and penalizes a stone that is not similar. An advanced grading system should prize a “uniqueness” of any good stone.





Regards,



Sergey and Yuri.

 

[strmrdr]

Interesting reading.
It is a common problem these days the measuring devices have become so precise that you have to figure out where the line is between a real world variation and one that is just a laboratory number.

A lot of industries have faced this.

As an example Iv seen industrial parts made using older less precise methods of manufacturing that have been around for a longtime fail when made on modern machines and held to ultra tight tolerances.
Striving for the ultimate in tight tolerances actually harmed the product.


When you have to take into account human perception variations it is even a harder task.


Take a real close look at some real famous paintings from 1 inch away they often look nasty and imprecise
Looked at from a distance they are beautiful.
Now design the same paining on a computer with everything aligned and in micron level precision placement and it will likely look awful and fake from any distance.
The one is technically and lab measurable "better" but not more desirable to a human.

 

[Garry H (Cut Nut)]

Intersting comments Strmrdr.

1. your first statement is the major issue.
2. your later statement may not aply to diamonds, although Sergey has mentioned that he thinks less symmetry may be beneficial in large diamonds - >10ct probably.

It is true that many cutters are developing cuts with extra facets. You can get a similar effect with some types of lessor symmetry for far less cost

Any other comments?
I know it is pretty heavy reading - but it is worth printing and reading over coffee.