Synthetic Cubic Zirconia (or CZ / American Diamond) is the cubic crystalline form of zirconium dioxide (ZrO2). 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). It is sometimes erroneously called "cubic zirconium".

Because of its low cost, durability, and close visual likeness to diamond, synthetic cubic zirconia has remained the most gemologically and economically important competitor for diamonds since commercial production began in 1976. Its main competitor as a synthetic gemstone is the more recently cultivated material, synthetic moissanite.

Chemical Composition: 

Zirconium Oxide - ZrO₂

Classification / Type: 

C.Z. is a man made material. The term synthetic is used to refer to this material, even though it does not have a natural counterpart, but it exists in the mineral Baddeleyite which crystallizes in monoclinic system.

Colors / Varieties: 

All colors. Transparency: Transparent to Opaque.

Crystal System / Forms: 

Cubic System

Hardness: 

8 - 8.5

Specific Gravity: 

5.60 - 6.2

Cleavage / Fracture: 

Nil / Conchoidal fracture

Optic Character: 

Isotropic (S.R.)

Lustre: 

Adamantine

Refractive Index / Birefringence: 

2.15

Pleochroism: 

Nil

Dispersion: 

0.060

Magnification: 

Gas bubbles, zirconium oxide powder droplets in rows, dispersive fire (orange) on pavilion facets.

U.V. Fluorescence: 

Generally strong yellow to orangish yellow. Varies with dopants used.

Spectrum: 

Varies with dopants used.

Cause of Color: 

• Green: Chromium
• Orange / red: Cerium, etc.

Specific Tests: 

Low see through effect.

Synthesis: 

Skull Melting Method

Simulants (with separation tests): 

Synthetic Moissanite (doubling, dispersion, inclusions), G.G.G.. (S.G., dispersion), Y.A.G. (S.G. dispersion), Diamond (S.G., dispersion, U.V. fluorescence), Strontium Titanate (dispersion, S.G.), Sphene (optic character, doubling, dispersion), Synthetic Rutile (dispersion, S.G., doubling), Demantoid (inclusions, dispersion, S.G.), Spessartite Garnet (inclusions, spectrum, S.G.), Malaya Garnet (inclusions, spectrum, S.G.), etc.

Geological Occurrence: 

In a laboratory. No natural counterpart.

Cuts & Uses: 

Facetted cuts, beads, etc.