First things first: Moissanite is not a diamond. Many people refer to is as a diamond simulant since it does not have the same material properties as a diamond (which is a mineral form of Carbon). Moissanite can be produced nearly colorless, has a Mohs hardness of 9.5, an a refractive index of 2.65; so slightly softer and more refractive than diamond. Moissanites are about 15%-18% lighter than diamonds so they cannot be sized based on weight (1ct, 1.5 ct). Instead, they are priced based on their measurements (6mm, 7.5mm).