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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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27 of 27 gemstone entries

Quick overview

Moonstone

Moonstone is a feldspar whose layered structure scatters light into a soft, moving glow called adularescence. Learn what causes it, what quality looks like and why it needs care.

Classification
Mineral variety
Mohs hardness
6–6.5 (scratch resistance — one part of durability)
Wear considerations
Moonstone is 6 to 6.5 on the Mohs scale, has poor toughness and has two cleavage directions, so a hard blow can break it. Manufacturers usually set it in pendants, earrings and pins rather than rings, which take more knocks. [cite ref="s3"]
Treatment
Typically untreated
Care
Clean moonstone with warm, soapy water only. Ultrasonic and steam cleaners are not recommended for it. Keep moonstone away from high heat and sudden temperature changes, which can crack it. It is…
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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.