One of the hardest substances on earth, only a diamond is hard enough to cut other diamonds. Polishing and mounting add brilliance to the stone and increase it's value. Diamond cutting can be traced back to the late Middle Ages. Prior to this time, diamonds were used in their natural octahedral state. The first improvements on nature's design involved a polishing of the crystal faces, which was called the "Point Cut". As further refinement progressed, one half of the crystal would be cut off, creating the "Table Cut". At the time, diamonds were valued primarily for their luster and hardness. Table Cut diamonds appeared black to the eye. In 1375, the guild of diamond polishers was formed in Nürnberg.
In the diagram of a "Round Cut" diamond (above and below), you will see that there are 8 "star" facets, 8 "kite" facets, 16 "upper girdle" facets, 16 "lower girdle" facets, 8 "pavilion" facets, 1 "culet" facet on the bottom, and one "table" facet on the top of the stone.
In 1475 Lodewyk van Berquem, a Flemish polisher of Bruges, introduced the concept of absolute symmetry in the disposition of facets. His work produced the "Pendeloque" or "Briolette" cut. During the middle of the sixteenth century, the "Rose" or "Rosette" cut was introduced. The "Brilliant" cut was introduced in the middle of the seventeenth century. The first Brilliants were known as Mazarins, and had 17 facets on the crown. They are referred to as Double-Cut Brilliants.
A Venetian polisher named Vincent Peruzzi introduced the Triple-Cut Brilliant by doubling the number of crown facets from 17 to 33; however diamonds of that particular cut seem dull compared to more modern cuts.
In the early 1900's, the development of diamond saws and jewelry lathes enabled the development of modern diamond cuts, including the Round Brilliant cut. The modern Round Brilliant consists of 58 facets - 57 if the culet is excluded. There are 33 on the crown and 25 on the pavilion. In recent decades, most girdles are faceted. Many girdles have 32, 64, 80, or 96 facets.
Even with modern techniques, the cutting and polishing of a diamonds resulted in a loss of as much as 50% of the stone's total weight. The round brilliant cut is preferred when the crystal is an octahedron, as two stones could be cut from one crystal. Asymmetrical crystals such as macles are usually cut in a "Fancy" style.
Popular fancy cuts include the "Baguette" (bread loaf), "Marquise" or "Navette" (little boat), "Princess" (square outline), "Heart", "Briolette" (a form of Rose cut), and the Pear. The "fancy cuts" are generally not held to the same strict standards as Round Brilliants.
In the 1970s, Bruce Harding developed new mathematical models for gem design. Since then, several groups have used computer models and specialized scopes to design new diamond cuts.
During the 1990s Israeli interests acquired about 20% of the diamond trade, buying diamonds from Russia and from mines in Africa that were not controlled by De Beers. De Beers now deals exclusively in diamonds from their own mines. A substantial diamond cutting industry has grown up in Gujarat provence, India where a workforce of around 800,000 people cut 90% of the world's diamonds.
Diamonds have long been prized as a component of jewelry design due to their high light dispersion and extreme hardness. The large trade in gem-grade diamonds is primarily controlled by the De Beers company, which has used its monopoly to manipulate prices. Unlike precious metals such as gold or platinum, there is a substantial mark-up in the sale of diamonds but a limited market for resale of diamonds. Therefore, their "investment" value is sentimental rather than monetary.
At one time it was thought over 80% of the world's rough diamonds passed through the De Beers subsidiary of DTC (Diamond Trading Company) of London, but presently the figure is estimated at around 60%. In the late 1990s, Canadian prospectors discovered several rich new sources of diamonds. The Ekati Diamond Mine, opened in 1998, produces 3 million carats of rough diamonds every year. The Canadian Diavik Diamond Mine was newly opened in 2004.
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