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Most true synthetic alexandrite is grown by the Czochralski method, known as “pulling”.Another method is a “floating zone”, developed in 1964 by an Armenian scientist Khachatur Saakovich Bagdasarov, of the Russian (former Soviet) Institute of Crystallography, Moscow.
Tairus (Russian: Тайрус, a portmanteau of Тайско and Русский ()) is a synthetic gemstone manufacturer. It was formed in 1989 as part of Mikhail Gorbachev's perestroika initiative to establish a joint venture between the Russian Academy of Sciences and Tairus Created Gems Co Ltd. of Bangkok, Thailand.
Alexandrite in sizes over three carats are very rare. Today, several labs can produce synthetic lab-grown stones with the same chemical and physical properties as natural alexandrite. Several methods can produce flux-grown alexandrite, Czochralski (or pulled) alexandrite, and hydrothermally-produced alexandrite.
Demantoid is the green gemstone variety of the mineral andradite, a member of the garnet group of minerals.Andradite is a calcium- and iron-rich garnet.The chemical formula is Ca 3 Fe 2 (SiO 4) 3 with chromium substitution as the cause of the demantoid green color.
The Alexandrit class, Russian designation Project 12700 Aleksandrit (for the mineral alexandrite), is the newest class of Russian minesweepers designed by Almaz and being built by the Sredne-Nevsky Shipyard for the Russian Navy. The first ship was laid down on 22 September 2011 and was launched in June 2014. Anywhere between 30 and 50+ ships ...
Chrysoprase, chrysophrase or chrysoprasus is a gemstone variety of chalcedony (a cryptocrystalline form of silica) that contains small quantities of nickel.Its color is normally apple-green, but varies from turquoise-like cyan to deep green.
Emerald of Saint Louis, [5] 51.60 carats cut; discovered in Austria, probably Habachtal, resides in the National Museum of Natural History, Paris; Gachalá Emerald [6] 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]
Natural History Museum, London: Emerald of Saint Louis [49] Austria, probably Habachtal 51.60 carats cut National Museum of Natural History, Paris Gachalá Emerald [50] Colombia, 1967 858 carats uncut National Museum of Natural History, Washington Mogul Mughal Emerald: Colombia, 1107 A.H. (1695–1696 AD) 217.80 carats cut