Sapphires ‘Heat Treated with Additives’

Ted Themelis, research gemologist, author, and corundum expert in Thailand, would like to excise the term "bulk diffusion" from the gemological vocabulary. Bulk diffusion refers to the heat treatment that infuses foreign elements that can affect color change in corundum. "There is no need to introduce the unpopular—but scientifically correct—bulk-diffusion term, which refers to ion transportation phenomenology applied to all treated gems," Themelis says. "Jewelers and gem dealers are not scientists but gem traders seeking easy communication that properly represents the product they sell." Here is Themelis's proposed disclosure statement: Gem species: Natural Corundum Enhancement: Enhanced by heat Treatment classification: HEAT-TREATED (with additives)* Comments: *Additive compounds including beryllium-bearing substances may have been used in the process. The resulting col
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