Diamond cutting

Cutting diamonds requires specialized knowledge, tools, equipment, and techniques because of its extreme difficulty.

The first guild of diamond cutters and polishers (Diamantaire) was formed in 1375 in Nuremberg, Germany,[1] and led to the development of various types of "cut".

[3] Diamonds are cut and polished in Surat, India and the Chinese cities of Guangzhou and Shenzhen.

[5] The basic diamond cutting process includes these steps; planning, cleaving or sawing, bruting, polishing, and final inspection.

The actual process also includes many more stages depending on the size and quality of the rough stone.

For example, bigger stones are first scanned to get the three-dimensional shape, which is then used to find the optimal usage.

The scanning may be repeated after each stage and bruting may be done in several steps, each bringing the girdle closer to the final shape.

Also, inclusions are photographed and placed on the 3D model, which is then used to find an optimal way to cut the stone.

Physical factors include the original shape of the rough stone, and location of the inclusions and flaws to be eliminated.

The weight retention analysis studies the diamond rough to find the best combination of finished stones as it relates to per carat value.

Even with modern techniques, the cutting and polishing of a diamond crystal always results in a dramatic loss of weight, about 50%.

[7] Sometimes the cutters compromise and accept lesser proportions and symmetry in order to avoid inclusions or to preserve the weight.

[8] Cleavage can be along any of the four planes parallel to the faces of an octahedral diamond (i.e. perpendicular to body diagonals of the unit cell).

This is done to ensure maximum weight, clarity and best angles for the specific shape of diamond.

In the 18th century there was a trend for recutting Indian diamonds to suit English tastes.