Method of carbon 14 dating
The most familiar uses of diamonds today are as gemstones used for adornment, a use which dates back into antiquity, and as industrial abrasives for cutting hard materials.The dispersion of white light into spectral colors is the primary gemological characteristic of gem diamonds.The popularity of diamonds has risen since the 19th century because of increased supply, improved cutting and polishing techniques, growth in the world economy, and innovative and successful advertising campaigns.In 1772, the French scientist Antoine Lavoisier used a lens to concentrate the rays of the sun on a diamond in an atmosphere of oxygen, and showed that the only product of the combustion was carbon dioxide, proving that diamond is composed of carbon.These two different source of carbon have measurably different —150 km (93 mi) or more (three times or more the depth of source magma for most volcanoes). These typically small surface volcanic craters extend downward in formations known as volcanic pipes.The pipes contain material that was transported toward the surface by volcanic action, but was not ejected before the volcanic activity ceased.Most natural diamonds are formed at high temperature and pressure at depths of 140 to 190 kilometers (87 to 118 mi) in the Earth's mantle.
The word is from the ancient Greek ἀδάμας – adámas "unbreakable".
During eruption these pipes are open to the surface, resulting in open circulation; many xenoliths of surface rock and even wood and fossils are found in volcanic pipes.