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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Salt-and-pepper diamond
Hardness 10
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Sapphire
Hardness 9
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Spinel
Hardness 8
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Quick overview
Salt-and-pepper diamond
A natural diamond with many visible inclusions. Heavily included black diamonds still rank 10 on the Mohs scale [cite ref="s6"]. Many inclusions near the edge make chipping more likely [cite ref="s1"].
- Classification
- Trade description within the mineral species diamond
- Mohs hardness
- 10 (scratch resistance — one part of durability)
- Wear considerations
- Heavily included black diamonds still rank 10 on the Mohs scale, but their many tiny fractures can make them more brittle and prone to chipping if struck sharply [cite ref="s6"]. Diamond is only somewhat tough, and many inclusions near the girdle or points make chipping more likely [cite ref="s1"]. Points are better protected by bezels, partial bezels or V-shaped prongs.
- Treatment
- Laser drilling to improve clarity, Fracture filling to improve clarity (not permanent), Heating to graphitise fractures and turn a greyish, heavily fractured diamond black
- Care
- Clean your salt-and-pepper diamond with mild soap and water. Skip ultrasonic and steam cleaners, which are not advised for heavily included black diamonds. Avoid hard knocks, such as against countertops, and avoid…
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.