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Properties of Cubic Zirconium

Cubic zirconium was developed in the 1970s in the Soviet Union for use in lasers. Although two small naturally occurring crystals were discovered in Germany in 1937, the microwave technology for making these crystals didn't exist until decades later. Initially, Soviet lasers were designed to use rubies, but the scarcity of rubies in the Soviet Union initiated a search for a synthetic gem that could be used in laser research. The cubic zirconium resulted from this search. The names CZ, cubic zirconia, and cubic zirconium all refer to the crystalized form of the metal zirconium.

Hardness
- Cubic zirconium ranges in hardness from 8.25 to 9 on the Mohs scale. Since cubic zirconium is often used to approximate diamonds in jewelry, this compares to a diamond hardness of 10.
Refraction
- Cubic zirconium's refraction index is 2.17, compared to a diamond's refraction index of 2.42.
Dispersion
- Cubic zirconium and diamond disperse light differently. Cubic zirconium's dispersion index is 0.066, while a diamond's index is 0.044.
Specific Gravity
- Cubic zirconium is heavier than diamond. Cubic zirconium's specific gravity is 5.8. A diamond's specific gravity is 3.52.
Chemical Composition
- The main chemical component of cubic zirconium is zirconium oxide. Zirconium oxide is a metal. When trace elements are added and the metal is heated to high temperatures in an industrial microwave, the metal crystallizes to form a cubic zirconium crystal.

Gemology