How does depth affect a colored stone?

[beaujolais]

How does depth affect a colored stone?

I''m more familiar with how it affects diamonds.

Thanks so very much.

 

[myanmargems]

If there is no depth, the stone is we call window and value much less than the one with enough deph with fire.

 

[Harriet]

A deeper stone also appears more saturated.

 

[Richard M.]

Date: 5/16/2008 5:13:22 PM
Author:sonomacounty
How does depth affect a colored stone?


I''m more familiar with how it affects diamonds.


Thanks so very much.

It depends on the stone variety and its index of refraction. Basically colored gems should be cut at appropriate angles to allow the maximum amount of light to be reflected back to the viewer''s eye, just as with diamonds. But each colored gem variety has its own "critical angle." If pavilion facets are cut below the c/a light will "leak" through the stone''s bottom instead of being reflected back out, resulting in a "windowed" stone.

Conversely, "belly cut" gems with too much weight (depth) and improper angles below the girdle show extinction or a lack of brilliance. Sometimes badly-cut stones have both excess weight and display windowing due to very shallow angles at the culet.

It''s important to recognize that no hard and fast rules can be created for all colored gem cutting styles. Most of the above applies to round stones. Other shapes have their own peculiarities. Cut is often a matter of personal taste. Many gems like emerald are cut for maximum color saturation, not brilliance, so different rules/tastes apply. There are nearly endless variations.

Richard M.

 

[marcy]

Since you already have some great answers I would also add if you have a stone with extra depth you''ll pay for it in carat weight as well.

 

[beaujolais]

Thanks, knowledgable friends !