<P> Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boron and nitrogen . Small amounts of defects or impurities (about one per million of lattice atoms) color diamond blue (boron), yellow (nitrogen), brown (lattice defects), green (radiation exposure), purple, pink, orange or red . Diamond also has relatively high optical dispersion (ability to disperse light of different colors). </P> <P> 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 . Carbon - containing minerals provide the carbon source, and the growth occurs over periods from 1 billion to 3.3 billion years (25% to 75% of the age of the Earth). Diamonds are brought close to the Earth's surface through deep volcanic eruptions by magma, which cools into igneous rocks known as kimberlites and lamproites . Diamonds can also be produced synthetically in a HPHT method which approximately simulates the conditions in the Earth's mantle . An alternative, and completely different growth technique is chemical vapor deposition (CVD). Several non-diamond materials, which include cubic zirconia and silicon carbide and are often called diamond simulants, resemble diamond in appearance and many properties . Special gemological techniques have been developed to distinguish natural diamonds, synthetic diamonds, and diamond simulants . The word is from the ancient Greek ἀδάμας--adámas "unbreakable". </P> <P> The name diamond is derived from the ancient Greek αδάμας (adámas), "proper", "unalterable", "unbreakable", "untamed", from ἀ - (a -), "un -" + δαμάω (damáō), "I overpower", "I tame". Diamonds are thought to have been first recognized and mined in India, where significant alluvial deposits of the stone could be found many centuries ago along the rivers Penner, Krishna and Godavari . Diamonds have been known in India for at least 3,000 years but most likely 6,000 years . </P> <P> Diamonds have been treasured as gemstones since their use as religious icons in ancient India . Their usage in engraving tools also dates to early human history . 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 . </P>

Where was the first diamond mined in the world