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Main sapphire-producing countries Sapphire is a precious gemstone , a variety of the mineral corundum , consisting of aluminium oxide ( α- Al 2 O 3 ) with trace amounts of elements such as iron , titanium , cobalt , lead , chromium , vanadium , magnesium , boron , and silicon .
As the Yogo mines were still owned by the English, the United States government could not control those operations, so the mines were little affected by the war, even though industrial sapphires were critical to the war effort. [68] The Yogo Sapphire Mining Corporation of Billings, Montana, was the next company to try to run the English Mine ...
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Fancy sapphires of various colours are also available. In the United States, blue sapphire tends to be the most popular and most affordable of the three major precious gemstones (emerald, ruby, and sapphire). Turquoise Turquoise is found in only a few places on Earth, and the world's largest turquoise-producing region is the southwest United ...
Main ruby producing countries. Ruby is a pinkish red to blood-red colored gemstone, a variety of the mineral corundum (aluminium oxide). Ruby is one of the most popular traditional jewelry gems and is very durable. Other varieties of gem-quality corundum are called sapphires.
The five cardinal gems. Clockwise from top: sapphire, ruby, emerald, amethyst, diamond. Cardinal gems are gemstones which have traditionally been considered precious above all others. The classification of the cardinal gems dates back to antiquity, and was largely determined by ceremonial or religious use as well as rarity. [1]
Main jade producing countries. Jade is an umbrella term for two different types of decorative rocks used for jewelry or ornaments.Jade is often referred to by either of two different silicate mineral names: nephrite (a silicate of calcium and magnesium in the amphibole group of minerals), or jadeite (a silicate of sodium and aluminum in the pyroxene group of minerals). [1]
Asterism on the surface of a blue star sapphire. A purple-pink star sapphire displaying asterism in a platinum ring.. An asterism (from Ancient Greek ἀστήρ (astḗr) 'star' and -ism) is a star-shaped concentration of light reflected or refracted from a gemstone.