Diamond Cutting

As every diamond is different, a stone must first be carefully examined by the cutter and then marked for cutting. Of all the cuts, the most popular is the round brilliant because of its ability to give a stone the greatest possible brilliance and fire with the most minimal amount of weight loss. The following cutting and polishing procedures uses the round brilliant cut as an example.

The rough diamond is divided into two parts by sawing or cleaving. Most stones are sawn across the "grain" (visible evidence of the diamond's crystal structure) by a paper-thin metal disc coated with diamond dust revolving at high speed or by laser. The stones that are marked for cleaving are split along the grain by a single blow from a steel blade.

After cleaving or sawing, the corners of the diamond are rounded off by a process known as bruting or girdling (only round brilliant cuts require this step). The stone is cemented into a "lathe", a holder that fits on a turning shaft. Another diamond is cemented to the end of a long rod held under the bruter's arm. As the lathe rotates, the two diamonds are brought together and grinded to shape. Diamond dust is produced from this action and is used in further sawing and faceting.

The brilliant now has a girdle-a sort of rim at the widest part by which it is usually set. The size or position of the girdle should not change throughout the rest of the diamond cutting process.