Cubic zirconia (
CZ) is the cubic crystalline form of
zirconium dioxide (ZrO
2). The synthesized material is hard, optically flawless and usually colorless, but may be made in a variety of different colors. It should not be confused with
zircon, which is a
zirconium silicate (ZrSiO
4). It is sometimes erroneously called "cubic zirconium".