Photo: Greg Polley, Smithsonian National Museum of Natural History
Zircon
Zircon
High dispersion and brilliance - not to be confused with cubic zirconia.
- Mohs hardness
- 6–7.5
- Crystal system
- Tetragonal
- Composition
- ZrSiO₄
- Colours
- Blue, Colourless, Yellow
- Origins
- Cambodia (Ratanakiri - finest blues), Tanzania, Sri Lanka
- Birthstone
- December
Natural zircon is one of the oldest minerals on Earth - the oldest known terrestrial crystal (4.4 billion years) is a zircon from Western Australia. It has high refractive index and dispersion, giving cut gemstones outstanding fire.
Most commercial blue zircon is heat-treated brown material from Cambodia. Cubic zirconia is an unrelated lab-grown diamond simulant - not the same gem.
Treatments
What to know
- Heat treatment - standard for blue and colourless varieties
Care & handling
How to wear it
- Brittle - protect from sharp impact
- Avoid ultrasonic and steam
Jewellery use
Setting the gemstone
Pendants, earrings and protected ring settings.