A clear crystal with the general appearance of diamond when viewed from reasonable distance. Most often used in costume jewelry. A Cubic Zirconium is not as hard as a diamond (7.5 to 8.5 on the Mohs scale vs. 10 for a diamond) and will show wear on the facet edges with routine wear. CZ is about 75% heavier than diamond. Dispersion differs between a Cubic Zirconium and that of a diamond. Dispersion occurs based on the gemâ€™s refractive index. In this case, refractive index simply indicates how much a beam of light will bend, based on the direction in which it is traveling when it passes between two materials of different optical densities (such as between diamond and air; or between CZ and air). Being that CZ has a refractive index of 2.176, compared to a diamond's 2.417, therefore, diamonds are brighter than CZ.
Synthetic diamond/ gemstone