Q: How does Moissanite compare to diamonds? A: Moissanite is very close to diamond in characteristics. The refractive index (brilliance) of a diamond is 2.42 and Moissanite is 2.65. The dispersion (fire) of diamond is 0.044 and Moissanite is 0.104. Moissanite's brilliance and fire exceeds that of a diamond. The hardness of a diamond is 10 and Moissanite is second at 9.25 which is harder than ruby (9), sapphire (9) or emerald (7.5). These characteristics make Moissanite more superior to diamonds and very difficult for anyone to tell Moissanite from a diamond. Moissanite is generally priced at about a tenth of the cost of a comparable diamond. (Click for Comparison Chart)