Zircon is a natural gem mineral that comes in many colors. Colorless zircon is well known for its brilliance and fire.
Properties
| Refractive index | 1.925 to 1.984 (+/-0.040) (high zircon) |
|---|---|
| Birefringence | 0.036 to 0.059, usually 0.059 (high zircon) |
| Optic character | Doubly refractive (uniaxial) |
| Dispersion | 0.039 |
| Specific gravity | 4.60 to 4.73, usually about 4.70 (high zircon) |
| Hardness (Mohs) | 7.5 (high zircon); 6 to 7.5 from low to high |
| Crystal system | Tetragonal |
| Pleochroism | Strong: blue, colorless to gray |
| Absorption spectrum | Prominent sharp line in the red, the typical uranium pattern, 653 nm (U (uranium)) |
Published values. They change a little from stone to stone. Our tools do not model zircon yet. Sources: GIA · International Gem Society · Gemdat
In more detail
Its brilliance and fire are close enough to diamond's to explain centuries of confusion. Zircon is a zirconium silicate, and GIA says it is unfairly confused with cubic zirconia. Heat treatment commonly produces blue and colorless zircon, and some stones revert after long light exposure. Radiation can damage the crystal structure of some zircons, but almost all jewelry zircons are the high type. Zircon can be brittle, so protect it from rough wear and do not use steam or ultrasonic cleaners.
Related terms
- Cubic zirconia: Cubic zirconia (CZ) is a man-made diamond simulant. GIA names it as the most common simulant today.
- Diamond: Diamond is a single element, carbon, with every atom bonded to four neighbors in a cubic crystal. It is the hardest gem, Mohs 10.
- Simulant: A simulant is a material that looks like a gem but has a different chemistry, structure and properties. Cubic zirconia, moissanite and glass are diamond simulants.
- Heat treatment: Heat treatment is controlled heating of a gem to change its color or clarity.
- Fire: Fire is the flashes of spectral color that a cut stone sends out. In our census, fire is the share of returned light whose colors leave more than 0.6° apart.
- Birefringence: Birefringence is the difference between the two refractive indices of a doubly refractive stone. It shows how strongly the stone splits light into two rays.