Comes in two forms: high or normal zircon with good physical and optical properties, and low zircon (green) where radioactive decay has progressed to the point that they can be almost amorphous in structure and their properties are much lower (SG 4.0, RI 1.80, critical angle 34°).

Physical properties:

Chemistry: Zr[SiO4]
SG: 4.6 – 4.7
Cleavage: Imperfect, two directions
Fracture: Brittle
Heat sensitivity: None

Optical properties:

RI: 1.92–2.01
Dispersion: 0.038 (medium)
Double refraction: 0.06 (high)
Pleochroism: Weak
Critical angle: 31°

Facet angles (pavilion/crown):

Vargas: 41°/37°
Soukup: 42°/37°
Roth: 41°/35°
MDR: 41°/35°
Schlagel: 40°/36°
Hashnu: 41°/37°
Sinkankas: 40°/40°
GIA: 41°/40°
Perkins: 39°/43°
Raytech: 42°/37°

Cutting lap:

All grit sizes

Facet polishing:

Vargas: Aluminium oxide on tin/lead or tin
Soukup: Aluminium oxide on tin
Christiansen: Aluminium oxide on tin/lead or tin, diamond 50k/100k on steel
Perkins: Aluminium oxide on BATT or Corian
MDR: Aluminium oxide on tin, 14-50k diamond on zinc
Raytech: Aluminium oxide on Fast Lap, tin or phenolic

Cabochon polishing:

Christiansen: Aluminium oxide, tin oxide, or diamond 50k or 100k on leather or wood


The high double refraction can make larger stones appear "blurry" if the table facet is not perpendicular to the crystal axis.


Brown stones are heat-treated to become blue or colorless.


Do not confuse it with the synthetic material cubic zirconia, which has completely different properties.

Zircon Rough

Zircon on Gemdat

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