Feature Gems & Gemology, Winter 1997, Vol. 33, No. 4

Synthetic Moissanite: A New Diamond Substitute

Kurt Nassau, Shane F. McClure, and Shane Elen, James E. Shigley

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A new diamond imitation, synthetic moissanite (silicon carbide), is now being produced by C3 Inc. in near-colorless form for jewelry purposes. With refractive indices of 2.648 and 2.691, a dispersion of 0.104, a hardness of 9¼ on the Mohs scale, and a specific gravity of 3.22, synthetic moissanite is much closer to diamond in overall appearance and heft than any previous diamond imitation. The thermal properties of synthetic moissanite are also so close to those of diamond that the thermal probes currently on the market react to synthetic moissanite as if it were “diamond.” This new material can be readily separated from diamond on the basis of its anisotropic optical character, which produces a doubling in the appearance of facet junctions. A new instrument manufactured by C3 Inc. solely to distinguish synthetic moissanite from diamond was also examined for this study.