Zircon

History
Zircon has been around for thousands of years. Originally mistaken for a diamond, colorless zircons have been used as diamond substitutes in ancient jewellery. Orangy yellow zircon has the ancient name jacinth, meaning gold colored.

Features
Zircon crystals are square prisms with a pyramid on either end, and are frequently short and squat. Zircon contains tiny amounts of radioactive material which contribute to changes in mass and color over time. With a hardness just above quartz, flawless stones wear well in jewellery.

Treatments
The radioactive elements present in zircon degrade the material over hundreds of years, making it an opaque brownish black. "Low" zircon will become rejuvenated if correctly heated, and will return to its former shades of green, blue, gold, colorless or pink.

Principal Deposits
Zircon can be found in Sri Lanka, Myanmar, Australia, New Zealand, Thailand, Nigeria and Tanzania.

Rarity 
Zircons are moderately rare, with the rarest being a deep blue rivaling deep blue sapphires for color.