Diamonds have been mined for centuries. The main locations were originally India and Brazil, but today they are also mined in South Africa, North America, Russia and Australia.

Of all the major precious gemstones, diamonds are the most famously valuable and generally recognizable as a white, brilliant stone. However, most people do not realize that diamonds are found in several colours.

Coloured diamonds

The most highly prized diamonds are referred to as  «fancy-coloured», and range in colour from yellow, brown, blue and green to red or even black in hues that run the scale from the palest hint of colour to deep shades. Natural coloration is due to a variety of factors, including chemical impurities within the stone. For example, nitrogen will result in yellow diamonds, while blue diamonds are caused by the presence of boron. Brown, pink and mauve diamonds are the result of a deformed chemical structure, while green diamonds are caused by naturel radiation.

Unlike white diamonds, there is no easy price guide with coloured diamonds, as this is such a complicated area of’ study and one which is constantly being reassessed.

White diamonds

The majority of diamonds seen today fit into the colourless category. There are four factors which are vitally important when assessing the value and desirability of a stone, commonly referred to as the four Cs: cut, colour, and clarity and carat weight.

Carat weight is the easiest of the factors to determine, and there are instruments to measure the weight of diamonds.

Colour is a one of the most important of the four Cs, because the more colourless a stone, the rarer it is. Diamonds are graded for colour from «D» (the finest white stone) to «Z», and this wide range shows how many colour variations there are simply within the white Stone category. A «D» grade stone resembles pure white with no hint of colour, while an «M» grade stone is tinted and very often slightly yellow or champagne-coloured

Determining the clarity, or purity, of a stone is of equal importance. Natural diamonds are pure crystallized carbon, and often the scones are formed with naturally occurring inclusions (flaws) within the stone. These inclusions can take the form of small, black carbon spots, misty patches, or what appear to be white cracks (called gletz marks).

All of these inhibit the brilliance of the stone. The fewer the inclusions in a stone the better clarity of the diamond.

The cut of the diamond is the final factor in determining its value. Many people confuse the «cut» with the «shape» of a diamond. The seven most popular shapes are the multifaceted brilliant-cut round, marquise, pear, oval and heart, and the simpler step-cut square and emerald cuts. Though shape does not determine value, shapes can be cut well or badly. Thus, while the other criteria (colour, clarity, carat weight) depend on nature, the cut is completely determined by human skill. The skills of the various craftsmen during splitting, sawing, shaping and polishing determine the cut or «make» of the diamond.

Ideally, as much light as possible should be reflected through the diamond. When a diamond is well cut, light enters the stone through the top facets and is then reflected from one facet to another and back out through the top. This effect is known as «refraction».