The process that sees a rough diamond reborn into a glistening masterpiece is nothing short of spectacular. Once mined and sorted, a diamond takes on average about 5 months to reach the market. During this time it undergoes quite a transformative journey thanks to the skills, patience and precision of some of the world’s most elite sculptors: the diamond cutters.
A mere 20% of all diamonds that reach sorting centres are of gem quality. That is, they are at least 99.95% carbon and more than 99.99% pure. Rough diamonds that make the grade are transferred to centres where masterful diamond cutters set to work sculpting the untouched stones into dazzling statement pieces.
THE ART OF CUTTING DIAMONDS
The first stage in the process of transforming a rough diamond into a polished gem is planning. Diamond cutters employ state-of-the-art technology to assess and analyse the roughs, determining the optimum way to cut the diamonds to maximise their value. At this stage, cutters also decide on the final shape of the diamond. The most popular is the round cut, giving the gem a beautiful form which maximises its brightness. Brilliant, modified cuts are also possible; these include the oval, marquise, heart and pear. Recently, classic shapes such as the cushion, Asscher, and emerald cut, have all seen a resurgence in popularity, as too have fancy cuts such as the princess cut. With the aid of a three-dimensional model of the rough, the stone is cleaved along its weakest point into smaller, more manageable pieces. This is done either with a steel blade, a rotating phosphorbronze saw or a laser. The cutter will then prime the gem for bruting, determining which part of the diamond will be the table (flat top) and which the girdle (outside rim). Its shape is formed by placing two diamonds on spinning axles that turn in opposite directions. They grind against one another to create the smooth finish of the girdle. The next stage is polishing the diamond. A spinning wheel coated in abrasive diamond powder smooths and creates the reflective facets that determine the gem’s final shape. It then undergoes a process of blocking and brillianteering to perfect its aesthetic composition. The finished diamond is inspected and then sent to a gemological laboratory for grading.
HIGH VALUE AND HIGHLY DESIRABLE DIAMONDS
Diamond cutters are skilled artisans whose utmost attention to detail produces some of the most sought-after gemstones in the world. But what determines a diamond’s value, and which ones are rare? Generally speaking, the cut, clarity (presence or absence of inclusions), carat (weight) and colour of a diamond determine its worth. But the actual chemical composition of the stone can also significantly affect its value. White diamonds vary considerably depending on their nitrogen content. These diamonds are graded on a scale from D (totally colourless) to Z (pale brown or yellow). The most valuable and rare have the least amount of nitrogen, which gives them a clear and transparent appearance, beautifully dispersing the light.
White diamonds are not the only ones to be highly prized and valuable. ‘Fancy’ diamonds with an intense colour, command an extremely high value. Only a small number are released to the market every year; as a result, they sell for the highest price per carat than any other gemstone. Fancies obtain their colour because of an impurity or defect in their structure. This naturally occurring phenomenon creates an intensity of colour that varies on a grading scale from fancy light, fancy to fancy intense and fancy vivid. The more highly concentrated the colour within the stone, the more it is worth.
Blue is one of the rarest fancies, with only 1 in 200,000 diamonds in the world possessing the colour. It is created when a small amount of boron is trapped in the crystal structure of a diamond. By contrast, green, purple and orange coloured diamonds form due to naturally occurring radiation in the rock where the diamond is present. It creates defects in the structure, which trap electrons that interact with the light to give the gem a coloured pigment. In the rarest stones, this colour penetrates the whole diamond. Other colours like red and pink result from a mechanical defect or stress in the diamond, caused by the tectonic forces that brought it to the surface. These defects trap electrons that interact with the light to produce pink or red shades. However, true red diamonds are extremely rare, most are a dark pink. With such skill and complex processes at work, it is easy to see why diamonds are so desirable and in some cases, uniquely rare.