Diamonds

Diamonds, long considered the most prized of gemstones, were first mined in India. Pliny may have mentioned them, although there is some debate as to the exact nature of the stone he referred to as Adamas; In 2005, Australia, Botswana, Russia and Canada ranked among the primary sources of gemstone diamond production.The British crown jewels contain the Cullinan Diamond, part of the largest gem-quality rough diamond ever found (1905), at 3,106.75 carats (621.35 g). Now popular in engagement rings, this usage dates back to the marriage of Maximilian I to Mary of Burgundy in 1477.

Diamond may be up to 3 billion years old

Diamond may be up to 3 billion years old, which is much older than their surface host rock (Harlow, 1998, p. 60). Diamond crystallization originates some 200 kilometers, or 320 miles, beneath the surface and the disaggregated crystals are merely transported to the surface via kimberlite and lamproite pipes (Harlow, 1998, p. 54). These igneous host rock formations are roughly cylindrical in shape and act as a conduit from the Earth's mantle to the contintental crust.Diamonds are differentiated between various types, Ia, Ib, IIa, and IIb. Although this information is important to the diamond cutter, it is of no value to the student merely interested in diamond as a gemstone. Diamond's superior optical properties and hardness has earned this mineral the highest respect in both industry and jewelry. It has a long tradition of invincibility and hence the Greek name, adamas.