Kurt Nassau and Edward A. Lewand, December 1, 1989
Low levels of radioactivity were found in some greenish yellow to yellow-green (peridot-like) synthetic spinel-and-glass triplets, mirror-backed glass rhinestone chatons and fully fashioned glass rhinestones.
Read MoreJames E. Shigley and Carol M. Stockton, March 1, 1984
Similarities between natural spinels - with intense blue colour - and synthetic material, have led to difficulties in the recognition of the natural stones by traditional methods.
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