Fluid Inclusions Confirm Authenticity of Tibetan Andesine Can Tibetan andesine now be certified ?

Introduction Untreated copper-bearing feldspar of a rich red color is found in nature, but gem-quality pieces are scarce. For decades the major occurrence has been in Oregon (USA), but gem-quality red feldspar also occurs in Japan (Furuya & Milisenda, 2009) and elsewhere. Beginning in 2002, gem-quality red plagioclase feldspar entered world gem markets. The source was originally stated as the Congo and later morphed into Tibet. By 2007, suspicions that such stones were the result of a treatment were widespread. These suspicions were confirmed in early 2008 (Furuya, 2008), when the treatment was revealed as one of copper diffusion into otherwise lightly-colored plagioclase. This was confirmed by laboratory experiments which replicated the treatment (Emmett & Douthit, 2009). Still, the question remained. Was there a genuine red feldspar mine in Tibet? If so, how would one separate such stones from the treated material? This question challenged the gemological community, resulting in several expeditions to the alleged Tibetan localities for sample collection and subsequent testing.