Ruby crystal and gems. Rubies are the red variety of the mineral corundum, which is itself a crystalline form of aluminium oxide with traces of iron,

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Ruby crystal and gems. Rubies are the red variety of the mineral corundum, which is itself a crystalline form of aluminium oxide with traces of iron, titanium and chromium. The red colour of a ruby is caused mainly by the presence of chromium.

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Keywords: aluminium, birthstone, chromium, corundum, crystal, crystalline, cut, gem, gemstone, geological, geology, mineral, mineralogy, oxide, polished, precious, red, ruby, specimen, variety