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  2. Corundum - Wikipedia

    en.wikipedia.org/wiki/Corundum

    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 ]

  3. Corundum (structure) - Wikipedia

    en.wikipedia.org/wiki/Corundum_(structure)

    Corundum is the name for a structure prototype in inorganic solids, derived from the namesake polymorph of aluminum oxide (α-Al 2 O 3). [1] Other compounds ...

  4. Sapphire - Wikipedia

    en.wikipedia.org/wiki/Sapphire

    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.

  5. Ruby - Wikipedia

    en.wikipedia.org/wiki/Ruby

    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]

  6. Black Star sapphire - Wikipedia

    en.wikipedia.org/wiki/Black_Star_sapphire

    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.

  7. Vietnam - Wikipedia

    en.wikipedia.org/wiki/Vietnam

    Vietnam, [e] [f] officially the Socialist Republic of Vietnam, [g] [h] is a country at the eastern edge of mainland Southeast Asia, with an area of about 331,000 square kilometres (128,000 sq mi) and a population of over 100 million, making it the world's fifteenth-most populous country.

  8. Adamantine spar - Wikipedia

    en.wikipedia.org/wiki/Adamantine_Spar

    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 ...

  9. Category:Corundum varieties - Wikipedia

    en.wikipedia.org/wiki/Category:Corundum_varieties

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