spectroscope
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Describing Color in Gems | A Fool's Guide
Color types such as "pigeon's blood," "Paraíba" and "cobalt blue" have become wildly popular in the gem trade. But there is a vast difference between coining such terms and applying them in a way that is both consistent and logical. Richard Hughes casts a critical eye on the subject.
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Gem Testing with the Spectroscope
Many gemologists have difficulty mastering the direct-vision spectroscope. This article eases the pain.