A Simple Procedure to Separate Natural from Synthetic Amethyst on the Basis of Twinning

Abstract

Dr. Karl Schmetzer recently showed h o w near-flawless to flawless natural amethyst could be separated from synthetic amethyst on the basis of the presence of Brazil twinning i n the natural stones. Whereas Dr. Schmetzer's procedure required a special apparatus, the authors have determined that a standard gemological polariscopeis more than adequate to make the separation i n most cases. Although some synthetic amethyst does show evidence of twinning, in the synthetic stones examined thus far i t has taken a form that i s distinctly different from the Brazil twinning seen i n most natural amethysts. The presence of certain inclusions as well as the nature of the color zoning seen in natural versus synthetic amethysts is of primary use in making a separation. However, where there are no inclusions or color zoning, the presence of Brazil twinning in the natural amethyst will usually make the distinction.