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Gemstone encyclopedia

Every gemstone, explained

What each stone is, how it wears in jewellery, and what to ask before you choose one. Browse by colour, or go straight to a letter.

This encyclopedia is educational. Inclusion does not confirm current Ralph Jacobs stock, sourcing, availability or suitability for a particular jewellery design.

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Quick overview · December · As listed by GIA

Zircon

Zircon is a natural mineral prized for its brilliance and fire, and often confused with man-made cubic zirconia. This entry covers its colours, heat treatment, durability and care.

Classification
Mineral species
Mohs hardness
6–7.5 (scratch resistance — one part of durability)
Wear considerations
Zircon is 6 to 7.5 on the Mohs scale with fair to good toughness, but it can be brittle. Facet edges can chip, especially on heat-treated stones, if the stone is not worn and handled carefully. It can be worn in all types of jewellery if you avoid rough wear and hard blows.
Treatment
Heat treatment to produce blue, colourless and yellow stones from brown rough (common; blue zircon is almost always heated). Named here under this guide's standard of always naming common treatments., Fracture filling (possible, but rarely used on zircon). Named here under this guide's standard of always naming treatments.
Recognised sources
General educational association
Care
Clean zircon with warm, soapy water. Ultrasonic and steam cleaners are not recommended for this stone. Store zircon so it does not rub against sapphire, ruby, diamond or other hard materials, and…
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Individual gemstones vary. Care depends on treatment, setting and condition. Encyclopedia inclusion does not confirm availability.

Individual gemstones vary · care depends on treatment, setting and condition · birthstone traditions vary · encyclopedia inclusion does not confirm availability.