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.
3 of 27 gemstone entries
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Laboratory-grown
Laboratory-grown diamond
Hardness 10
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Laboratory-grown
Laboratory-grown moissanite
Hardness 9.25
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Labradorite
Hardness 6–6.5
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Quick overview
Labradorite
Labradorite is a feldspar whose best pieces flash blue, green or gold against dark grey. Learn how the flash forms, how to judge it and how to wear it.
- Classification
- Mineral variety
- Mohs hardness
- 6–6.5 (scratch resistance — one part of durability)
- Wear considerations
- Labradorite rates 6 to 6.5 on the Mohs scale. It is brittle and has perfect cleavage, so it can break on impact. It scratches more easily than diamond, ruby, sapphire and emerald. For moonstone, a related feldspar, makers usually choose pendants, earrings and pins over rings, because rings take more knocks.
- Treatment
- Typically untreated
- Care
- For moonstone, a related feldspar, GIA names warm, soapy water as the only recommended cleaner and never recommends ultrasonic or steam cleaners. The sources for this entry give no separate cleaning guide…
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.