Cubic zirconia (CZ)
A synthetic, colourless crystal of zirconium dioxide used as an inexpensive diamond simulant.
Properties
- Hardness of about 8 to 8.5 on the Mohs scale, so it scratches and dulls more easily than diamond over years of wear.
- Refractive index of about 2.15 to 2.18, lower than diamond.
- Dispersion of about 0.058 to 0.066, higher than diamond, so it shows more coloured fire.
- Density much higher than diamond, so a CZ of the same size weighs considerably more.
Where CZ is used
CZ appears in fashion jewelry, silver jewelry, sample pieces and travel rings. Many jewelers also use CZ in prototypes to check a design before setting diamonds.
Rendering CZ
Use CZ values for IOR and dispersion when the product contains CZ. The result is a little less brilliant and a little more colourful than diamond, which matches reality. In listings, describe the stones as cubic zirconia, never as diamond, and avoid vague wording that suggests otherwise.
If you design a ring for diamonds but also sell a CZ version, render each version with its own gem material so both sets of images are honest.
CZ in CAD
CZ stones are cut in the same shapes as diamonds, so CAD stone libraries work without changes. Only the material changes in the render.