Moissanite is a Naturally Occurring Silicon Carbide. It is used as a Much Less Costly Substitute for Diamonds in Jewelry. Its Colors can range from D to K on the Diamond Color Scale and measures a Durable 9.25 on the Mohs hardness scale. Thought of as a Diamond Alternative, some of Moissanite's optical properties surpass those of Diamond. Lab-Grown Moissanite is also used widely in the making of Jewelry.