Gems : Cubic Zirconia

Cubic Zirconia, often abbreviated to CZ, is a synthetic stone used to simulate diamond. The oxide of zirconium, it’s induced to crystallise in the cubic system by being "doped" with small additions of other minerals, mainly yttrium or calcium. Cubic zirconia should not be confused with zircon, which is a rare, naturally occurring gemstone.
CZ is one of the most realistic diamond simulants ever produced, making it one of the best selling "gemstones". Most consumers buying a CZ ring have bought it as a diamond substitute, and believe that it looks like a real diamond ring. If CZs are mounted in real, high quality, diamond mounts, they are almost impossible to tell apart from diamonds with the naked eye.
CZ is quite hard, and retains its sparkle and polish well. However, as with all gemstones, be careful that it doesn’t rub against other gemstones, particularly diamonds, as this will cause wear & scratching.