Cubic Zirconia

Cubic zirconia is crystallographically isometric, an important attribute of a would-be diamond simulant. During synthesis zirconium oxide would naturally form monoclinic crystals, its stable form under normal atmospheric conditions. A stabilizer is required for cubic crystals to form, and remain stable at ordinary temperatures; this may be typically either yttrium or calcium oxide, the amount of stabilizer used depending on the many recipes of individual manufacturers. Therefore, the physical and optical properties of synthesized CZ vary, all values being ranges.

It is a dense substance, with a specific gravity between 5.6 and 6.0 — at least 1.6 times that of diamond. Cubic zirconia is relatively hard, 8–8.5 on the Mohs scale— slightly harder than most semi-precious natural gems.[1] Its refractive index is high at 2.15–2.18 (compared to 2.42 for diamonds) and its luster is vitreous. Its dispersion is very high at 0.058–0.066, exceeding that of diamond (0.044). Cubic zirconia has no cleavage and exhibits a conchoidal fracture. Because of its high hardness, it is generally considered brittle.

Under shortwave UV cubic zirconia typically fluoresces a yellow, greenish yellow or "beige". Under longwave UV the effect is greatly diminished, with a whitish glow sometimes being seen. Colored stones may show a strong, complex rare earth absorption spectrum.Cubi


Because of cubic zirconia's isomorphic capacity it can be doped with several elements to change the color of the crystal. A list of specific dopants and colors produced by their addition can be seen below.

Dopant[8][9] Symbol Color(s)
Cerium Ce yellow-orange-red
Chromium Cr green
Cobalt Co lilac-violet-blue
Copper Cu yellow-aqua
Erbium Er pink
Europium Eu pink
Iron Fe yellow
Holmium Ho Champagne
Manganese Mn brown-violet
Neodymium Nd purple
Nickel Ni yellow-brown
Praseodymium Pr amber
Thulium Tm yellow-brown
Titanium Ti golden brown
Vanadium V green