Synthetic moissanite: A new man-made jewel

Synthetic moissanite (silicon carbide, SiC) is a new man-made gemstone material developed and marketed by Charles and Colvard, Ltd., (formerly C3 Inc.) of Morrisville, USA. It provides exceptionally attractive and durable jewels, being second in hardness to diamond but not having diamond's pronounced cleavage. Synthetic moissanite can also serve as a diamond substitute, having properties overall closer to those of diamond than any other simulant: refractive indices 2.648 and 2.691 (diamond – 2.417), dispersion 0.104 (0.044), birefringence 0.043 (0), hardness 9–1/4 (10), specific gravity 3.22 (3.52). Thermal probes, in wide use for distinguishing diamond from all other simulants, usually give a 'diamond' reaction when testing synthetic moissanite. Diagnostics to the trained gemmologist for distinction from diamond are the birefringence, characteristic inclusions and subtle surface details.