Gemstone industrial abrasives, although larger gem-quality synthetic diamonds are becoming available in multiple carats. Whether a gemstone is a natural stone or lab-created (synthetic), the physical characteristics are the same. Lab-created stones tend to have a more vivid color to them, as impurities are not present in a lab and do not modify the clarity or color of the stone, unless added intentionally for a specific purpose. Gemstone A gemstone (also called a gem, fine gem, jewel, precious stone, or semi-precious stone) is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other
Tianshan Volcanic Group Chinese army) said that when climbing the Tianshan Mountains, saw "The Fire Mountains which send out masses of molten rock which flow for many Li" Tianshan Volcanic Group The Tianshan Volcanic Group is a volcanic field in the Tianshan Mountains in Northwest China. The historically active Cone of Pechan is within the group (also known as Peishan, Baishan, Hochan, Aghie, Bichbalick, Khala, and Boschan). The volcano is 440 km southwest of Urmqui, Xinjiang. Two eruptions are known from Tianshan, in 50 AD (± 50 years)and 650 AD (± 50 years). The book, Aspects of Nature in Different Lands and Different