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Elbaite is allochromatic, meaning trace amounts of impurities can tint crystals, and it can be strongly pleochroic. Every color of the rainbow may be represented by elbaite, some exhibiting multicolor zonation. Microscopic acicular inclusions in some elbaite crystals show the cat's eye effect in polished cabochons.
Each of the three notable types of opal – precious, common, and fire [3] – display different optical effects; therefore, the intended meaning varies depending on context. The general definition of opalescence is a milky iridescence displayed by an opal, which describes the visual effect of precious opal very well, and opalescence is ...
In 1912, to standardize birthstones, the (American) National Association of Jewelers (now called Jewelers of America) met in Kansas and officially adopted a list. [1]: 317 The Jewelry Industry Council of America updated the list in 1952 [3]: 311 by adding Alexandrite for June, citrine for November and pink tourmaline for October.
Today this tourmaline locality (type locality for dravite) at Dobrova (near Dravograd), is a part of the Republic of Slovenia. [9] Tschermak gave this tourmaline the name dravite, for the Drava river area, which is the district along the Drava River (in German: Drau, in Latin: Drave) in Austria and Slovenia.
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Upload file; Search. Search. Appearance. Donate; ... There are over 300 types of minerals that have been used as gemstones. Such as: ... Tourmaline subgroup: Achroite ...
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.
Austrian opaline glass bowl, 1914. Opaline glass is a style of antique glassware that was produced in Europe, particularly 19th-century France.It was originally made by adding materials such as bone ash to lead-crystal, creating a semi-opaque glass with reddish opalescence.