Cubic Zirconia:

Chemical Properties: ZrO2,

Hardness:8.5 Mohn's Scale

Reflective Index: 2.17

Specific Gravity : 5.65 - 5.95

Caring for Cubic Zirconia
Cubic Zirconia can be cleaned with any conventional jewelry cleaner or detergent.  With such a high hardness and durability, you can use a brush to clean off dirt or oil also.  Ultra clean jewelry cleaners may also be used on CZ and will not damage the stone.  However, when using soap leaving a film that will dull the brilliance of the stone.  Cubic zirconia should be cleaned frequently to remove oils from skin that also dull the brilliance of the gem.

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Cubic Zirconia (or CZ) is zirconium oxide (ZrO₂), a mineral that is extremely rare in nature but 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 of different colors. It should not be confused with zircon, which is a zirconium silicate (ZrSiO₄).

Because of its low cost, durability, and close visual likeness to diamond, synthetic cubic zirconia has remained the most gemologically and economically important diamond simulant since 1976.  Its main competition as a synthetic gemstone is the more recently cultivated material simulated moissanite.

Technical Aspects of Cubic Zirconia
Cubic zirconia is, as its name would imply, crystallographically isometric, and as diamond is also isometric, this is an important attribute of a would-be diamond simulant. Synthesized material contains a certain mole percentage (10-15%) of metal oxide stabilizer. During synthesis zirconium oxide would otherwise form monoclinic crystals, as that is its stable form under normal atmospheric conditions. The stabilizer is required for cubic crystal formation; it may be typically either yttrium or calcium oxide, the amount and 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 - 6.0. Cubic zirconia is relatively hard, at about 8.5 on the Mohs scale - nowhere near diamond, but much harder than most natural gems. Its refractive index is high at 2.15 - 2.18 (B-G interval) and its luster is subadamantine. 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. It is considered brittle.

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