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Gemstone Articles and Guides
Guides and reference articles on natural gemstones and minerals, grouped by subject.
4 articles · 2 subjects
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Gemstones & Minerals
2 articlesIn-depth guides to individual stones and their varieties: how they form, what they are made of, where they come from, and how to tell one from another.
- Formation
- Varieties
- Origins
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Gemology
2 articlesHow gemstones are identified and altered: hardness, refractive index, spectroscopy, testing instruments, and the treatments used on the stones you buy.
- Hardness
- Refractive index
- Treatments
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Corundum
Sapphire: The Many Colors of Corundum
A complete guide to natural sapphire: the chemistry behind its many colors, the world's major deposits, treatments and synthetics, and the famous stones and record crystals behind its reputation.
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Hardness
Gemstone Hardness and the Mohs Scale Explained
What hardness in a gemstone actually means, how the Mohs scale came about, why its steps are so uneven, and whether anything is genuinely harder than diamond.
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Hardness
Gemstone Hardness List
Mohs hardness values for more than 140 gemstones and gem materials, from talc at 1 to diamond at 10, with the mineral species behind each trade name.
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Corundum
Kashmir Sapphires: The Legend of the Blue Treasure
Why Kashmir sapphires outprice every other blue: the legendary Paddar mines, the science behind the velvety cornflower blue, and the records they set at auction.
Zodiac and birthstones
October's birthstones: Opal and Tourmaline
The stones traditionally linked to each zodiac sign and birth month, with links to the matching stones in the shop.