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Corundum is a crystalline form of aluminium oxide (Al 2 O 3) typically containing traces of iron, titanium, vanadium, and chromium. [ 3 ] [ 4 ] It is a rock -forming mineral . It is a naturally transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure. [ 7 ]
Padparadscha is a delicate, light to medium toned, pink-orange to orange-pink hued corundum, originally found in Sri Lanka, [11] but also found in deposits in Vietnam and parts of East Africa. Padparadscha sapphires are rare; the rarest of all is the totally natural variety, with no sign of artificial treatment.
Pages in category "Corundum gemstones" The following 7 pages are in this category, out of 7 total. This list may not reflect recent changes. B. Black Star sapphire; G.
When A is nonmetallic and B is metallic, the structure becomes the antiphase of corundum, called the anticorundum structure type, [8] with examples including β-Ca 3 N 2 [9] and borates. Ternary and multinary compounds can also exists in the corundum structure. The corundum-like structure with the composition A 2 BB'O 6 is called double ...
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. Ruby is one of the traditional cardinal gems, alongside amethyst, sapphire, emerald, and diamond. [3]
Black star sapphire, also known as 'natural star sapphire' is a type of corundum (aluminum oxide). It is usually cut into a dome shape to show a star feature. If it is cut with a flat or almost flat face, then a golden colour is revealed. The chemical composition and features for black star were analyzed in the Journal of Gemmology.
Adamantine spar is a silky brown variety of corundum. It has a hardness of 9 on the Mohs scale. [1] See also. Yogo sapphire; References This page was last edited ...
Vietnam remains a full member of the International Organisation of the Francophonie (La Francophonie) and education has revived some interest in the language. [392] Russian, and to a lesser extent German, Czech and Polish are known among some northern Vietnamese whose families had ties with the Eastern Bloc during the Cold War. [393]