Zircon suffers from its name. Many people assume it is the cheap imitation diamond. That is cubic zirconia, a different material altogether.
Zircon: a natural gemstone
Zircon is a natural mineral, and among the oldest on earth: zircon crystals found in Western Australia are more than four billion years old. As a gemstone it has remarkable brilliance and fire, more than most coloured stones. Before modern imitations existed, colourless zircon was the usual natural substitute for diamond.
Zircon occurs in brown, yellow, orange, red, green, blue and colourless. Blue is the most popular and is produced by heating brown zircon, much of it from Cambodia. The treatment is standard and the colour is generally stable.
Zircon is strongly doubly refractive: look through the top with a loupe and you see the facet edges at the back doubled. This is an easy way to tell it from diamond.
Wearing it. Zircon has a hardness of 6.5 to 7.5 on the Mohs scale, but it is brittle. The facet edges tend to chip and wear with knocks, so it does best in earrings and pendants, or in a ring with a protective setting that is worn with care. See which stones can be worn every day. Blue zircon is a birthstone for December.
Cubic zirconia: made in a laboratory
Cubic zirconia, often shortened to CZ, is synthetic zirconium oxide. It has been produced in large quantities since the 1970s as an inexpensive imitation of diamond. It is flawless, colourless and costs very little. It is fairly hard, around 8 to 8.5 on the Mohs scale, but over the years it scratches and turns dull in a way diamond does not. It is also noticeably heavier than a diamond of the same size.
Cubic zirconia has no connection with lab-grown diamond, which is real diamond, or with moissanite, another laboratory-made stone.
See zircon jewellery.
