Value Factors, Design, and Cut Quality of Colored Gemstones (Non-Diamond)

Posted on March 30, 2020 by Al Gilbertson, GG (GIA), CG (AGS)

In this comprehensive article, the author discusses thevalue factors of colored gems in five parts. This article looks at the first two parts. Future issues of the Gem Market News will continue the discussion, looking at other factors.

Part 1: Value Factors of Colored Gemstones

For our purposes, the word “cut” means more than just the shape of a gem; it also Value_of_a_Gemencompasses the elements of “cut quality.” Cut quality refers to how well the gem was manufactured, or how well various facets were placed. Combined with the proportions, symmetry, and polish, a well-cut gem should have a beauty that not only comes from its color and clarity, but from how the facets interact with light. This series should illustrate how to assess the elements of cutting, and how to better understand the impact of cut quality on the value of various gems. Part of that will include understanding the choices a cutter makes and why. While our focus is on forms of faceted gems, we will briefly touch on non-faceted gems.

The quality of the rough material limits the gemstone’s final appearance. Therefore cutters prefer rough that is transparent and without many inclusions. Some gems are rarely eye-clean, so some inclusions become acceptable in those materials. Since color is the highest priority for colored gems, how a cutter manages the light as it enters and exits a gem becomes an exercise in artistry. Ruby rough with a deeply saturated red color and free from even minor inclusions under 10X will produce gems of noteworthy face-up color and appearance, even if the fashioning is poor. But if the faceting washes out the color or muddies its color by…..

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