Diamonds are basically rough stones that have been shaped and faceted to bring out the most of their natural glow. The value of a diamond depends on the 4C: carat, colour (the less the better), clarity (lack of defects and inclusions), and cut (quality of faceting and reflectance).
Diamonds are made of carbon which is the hardest known mineral at 10 on Mohs scale. Diamond, or adamant, both come from Ancient Greek adamas meaning unbreakable.
Golconda deposits in India have long been the major source of diamonds; however, in early 18th century, another deposit was discovered in Brazil. Next century, many more fields were found in various regions to include Africa and Australia, both of which still produce many high-quality gems. In 1990s, rich deposits were come across in Canada that has recently made the top three in diamond mining.
The first Russian diamonds were found in early 19th century. In 1829, stones were discovered in the Ural mountains, and in 1949, in Yakutia. Today, Alrosa Holding does diamond discovery in Russia being one of the largest global players on the market.
Ancient thinkers mention various qualities of diamonds. Beside the correct concepts of its hardness, glow and clarity, many myths appeared. For example, the diamond authenticity was said to be best tested by beating it with a hammer, as due to the hardness, the hammer will break in two while leaving the diamond intact.
Diamonds vary in colour. Colourless diamonds are rare; the gems usually have a hint of yellow, brown or grey. Moreover, they can be intensely coloured and appear yellow, brown, orange, violet, green, pink, red, blue or black. The rare colours are red, green, and light blue.
The right shape for a diamond depends on the initial crystal form, thus the key idea of the cutting is to bring forth the inner beauty of the stone while keeping as much of the weight as possible. Traditional shapes include Round, Rose, Oval, Pear, Marquis, Princess, Baguette, Octagon, Radiant and other modifications (e.g. Cushion and Asscher). The Soviet cutting school was internationally renowned, Russian Cut having become a synonym of originality and high quality.