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Emerald is a gemstone and a variety of the mineral beryl (Be 3 Al 2 (SiO 3) 6) colored green by trace amounts of chromium or sometimes vanadium. [2] Beryl has a hardness of 7.5–8 on the Mohs scale . [ 2 ]
The "chelsea" filter was originally devised by Anderson and Payne in 1934 of the Gem testing Laboratory of the London Chamber of Commerce & Industry.The filter was devised with the collaboration of gemmology students of the Chelsea College of Science and Technology where Basil Anderson was an instructor for the Gemmological Association of Great Britain.
Helenite, also known as Mount St. Helens obsidian, emerald obsidianite, and ruby obsidianite, is a glass made from the fused volcanic rock dust from Mount St. Helens and marketed as a gemstone. [ 1 ] [ 2 ] Helenite was first created accidentally after the eruption of Mount St. Helens in 1980 .
Monarchs and the gem-loving royalty in India, Turkey, and Persia eventually sought the New World treasures once the gems arrived in Europe. These new emerald owners expanded their private collections with spectacular artifacts bedazzled with emeralds between 1600 and 1820, the time frame of Spain's control over the Colombian mines.
Zambia is the world's second biggest producer, with Kagem mine being the world's largest emerald mine [11] responsible for 25–30% of the world's production of gem-quality stones. [12] In 2019 Kagem emerald mine produced 42.4 million carats of emeralds. [13] The Zambian emerald sector is an important contributor of tax revenue to the Government.
When using the chart, it is important to remember these tips: Isotropic and opaque (metallic) minerals cannot be identified this way. The stage of the microscope should be rotated until maximum colour is found, and therefore, the maximum birefringence. Each mineral, depending on the orientation, may not exhibit the maximum birefringence.
Red beryl, formerly known as bixbite and marketed as red emerald or scarlet emerald, is an extremely rare variety of beryl as well as one of the rarest minerals on Earth. [1] [2]: 19 The gem gets its red color from manganese ions incorporated within the beryl crystal structure. [1] The color of red beryl is stable up to 1,000 °C (1,830 °F).
Mogul Mughal Emerald, 217.80 carats cut; mined in Colombia and cut in the Mughal empire in Hijri year 1107 (1695–1696), resides in the Museum of Islamic Art, Doha, Qatar [7] [8] Patricia Emerald, [9] 632 carats uncut, dihexagonal (12 sided); discovered in Colombia in 1920, resides in the American Museum of Natural History, New York, NY, US