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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Circumnavigate the boreal reaches of the globe to explore gems from polar regions.
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Chemically pure beryl is colourless, but trace elements give rise to green, blue and pink/red colours.
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The authors have encountered hundreds of polymer-filled aquamarines in the Chinese jewellery market.
Read MoreThis article, from the Spring 1991 issue of Gems & Gemmology, is a compilation of abstracts of important gemmology-related articles published outside of Gems & Gemmology.
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Aquamarine from granitic pegmatites of the Masino-Bregaglia Massif, Central Alps, Italy.
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