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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.
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 ...
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 ...
National Museum of Natural History, Washington [9] Star of Bombay: Sri Lanka 182 carats (36.4 g) Star Blue-violet National Museum of Natural History, Washington [10] Ruspoli Sapphire: 136.9 carats (27.38 g) [11] Stuart Sapphire: Sri Lanka 104 carats (20.8 g) Blue Tower of London [12] Bismarck Sapphire: Myanmar: 98.56 carats (19.712 g) Table Blue
Title page of a printed lapidary by Conrad Gessner of 1565. A lapidary is a text in verse or prose, often a whole book, that describes the physical properties and metaphysical virtues of precious and semi-precious stones, that is to say, a work on gemology. [1]
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]
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Depending on the desired colouration of the crystal, small quantities of various oxides are added, such as chromium oxide for a red ruby, or ferric oxide and titania for a blue sapphire. Other starting materials include titania for producing rutile, or titanyl double oxalate for producing strontium titanate. Alternatively, small, valueless ...