They have a Mohs hardness rating of 9.25 out of 10 and will test positive as diamonds on most handheld diamond testers. If you want a large carat, white gemstone, but you don’t have the money for a large diamond, moissanite is the way to go. It costs thousands less than Diamonds. 

Material: Silver
Material Finish: White Gold Plating
Stone Type: VVS Clarity D Color Moissanite Stones