Most natural diamonds are formed at high-pressure high-temperature conditions existing at depths of 140 to 190 kilometers (87 to 120 mi) in the Earth. 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 surface through deep volcanic eruptions by a magma, which cools into rocks known as Kimberlites. A Diamond has remarkable optical characteristics. Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as Boron and Nitrogen. Combined with wide transparency, this results in the clear, colorless appearance of most natural diamonds. Small amounts of defects or impurities (about one per million of lattice atoms) can produce, blue diamonds, red diamonds, pink diamonds, green diamonds and orange diamonds to name a few.
John Bassett
