sapphire(redirected from Yellow sapphire)
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sapphire,precious stone. A transparent blue corundumcorundum
, mineral, aluminum oxide, Al2O3. The clear varieties are used as gems and the opaque as abrasive materials. Corundum occurs in crystals of the hexagonal system and in masses. It is transparent to opaque and has a vitreous to adamantine luster.
..... Click the link for more information. , it is classified among the most valuable of gems. Sapphires are found chiefly in Madagascar, Sri Lanka, and Myanmar and also in Thailand, Tanzania, Australia, Cambodia, and in the United States (in Montana). The sapphires from Kashmir, which is no longer a significant source of the gems, are of a beautiful cornflower blue and are highly valued. The Sri Lankan and Madagascan varieties are paler; those from Montana have a metallic luster; those from Myanmar are a dark royal blue; and the Australian sapphires are of a dark blue shade approaching black. The terms yellow sapphire, purple sapphire, and green sapphire are used alternatively with Oriental topaz, Oriental amethyst, and Oriental emerald for other varieties of corundum. Like rubies of similar structure, some sapphires display a six-pointed star when cut to a cabochon (round-topped) shape and exposed to direct sunlight. Such star sapphires are usually obtained from Sri Lanka. Natural sapphires may be heat-treated to enhance their color. Synthetic sapphires are made by the fusion of aluminum oxide, with titanium oxide added as a coloring agent.
a variety of the mineral corundum (A1203), characterized by its dark or light blue color, which is caused by the simultaneous presence of the impurities Ti and Fe. Sapphire is a precious stone of order I. Star sapphire is characterized by as-terism in the form of a six-rayed star, which is brought about by microinclusions of rutile.
Sapphire deposits are mainly placers and usually contain rubies. Sapphires are found in the Southern Urals in the USSR and in Thailand, Sri Lanka, and India.
Synthetic sapphires that are used in the jewelry industry are obtained in the same manner as corundum. White sapphire is a synthetic colorless corundum that contains less than 0.001 percent impurities and has many specific physical properties that make it very useful in microelectronics, quantum electronics, high-resolution optics, and audio-optics.
REFERENCERubin i sapfir. Moscow, 1974.
A. S. MARFUNIN
What does it mean when you dream about a sapphire?
A precious stone of penetrating cobalt blue, the sapphire is associated with protection (e.g., by the archangel Michael).