A: Cubic Zirconia (or CZ) is zirconium oxide (ZrO2 ), is widely synthesized for use as a diamond simulant and it is a lab made created stone with a specific gravity of between 5.6-6.00 and at about 8.5 hardness on Mohs scale, which is harder than most natural gems. Its refractive index is high at 2.15 - 2.18 (B-G interval) and its luster is very good. Its dispersion is very high at 0.058 - 0.066, exceeding that of diamond (0.044).
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