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GIA's Gübelin Gem Project: Corundum

Ruby and sapphire (usually blue, but also in every other colour) have been the most important coloured gemstones for several thousand years. Originating historically in south-east and central Asia, and more recently in eastern Africa, these coloured varieties of the mineral corundum have been much sought as gems because of their rarity, colour and durability. Gem corundum can display asterism and chatoyancy due to the presence of oriented mineral inclusions, and in some cases, a change of colour when viewed under different light sources.

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GIA's Gübelin Gem Project: Spinel

Found in nearly every colour – most notably red, pink and blue – spinels are popular gemstones because of their abundance, moderate cost and attractiveness.

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GIA's Gübelin Gem Project: Various Gems, Taaffeite - Zoisite

Among the collection assembled by Dr Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

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GIA's Gübelin Gem Project: Various Gems, Sapphirine - Stibiotantalite

Among the collection assembled by Dr Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

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GIA's Gübelin Gem Project: Various Gems, Olivine - Rutile

Among the collection assembled by Dr Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

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GIA's Gübelin Gem Project: Various Gems, Kornerupine - Natrolite

Among the collection assembled by Dr Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

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GIA's Gübelin Gem Project: Various Gems, Danburite – Humite

Among the collection assembled by Dr Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

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GIA's Gübelin Gem Project: Various Gems, Barite - Cuprite

Among the collection assembled by Dr Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

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GIA's Gübelin Gem Project: Various Gems, Amblygonite - Axinite

Among the collection assembled by Dr Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

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Article
The ABCs of Pearls Reveal Fascinating Aspects of Gems from the Deep

“The A-Z of Pearls”, with at least one pearl-related subject for each letter of the alphabet, was presented in Thailand recently.

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