Cubic zirconia - Wikipedia Cubic zirconia (or CZ), the cubic crystalline form of zirconium dioxide (ZrO2), is a mineral that is widely synthesized for use as a diamond simulant. The synthesized material is hard, optically flawless and usually colorless, but may be made in a variety 02-24-2008 by alina1237 Tags diamond, russian cubic zirconia, wedding, wikipedia