Diamond (gemstone) Diamond (gemstone) A diamond (from the "adámas", meaning "unbreakable", "proper", or "unalterable") is one of the best-known and most sought-after gemstones. Diamonds have been used as decorative items since ancient times; some of the earliest references can be traced to 25,000 - 30,000 B.C. The hardness of diamond and its high dispersion of light—giving the diamond its characteristic "fire"—make it useful for industrial applications and desirable as jewelry. Diamonds are such a highly traded commodity that multiple organizations have been created for grading and certifying them based on the "four Cs", which are color, cut, clarity, and carat. Other characteristics,
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