Diamond Cutting: how to cut a diamond?
The 5 operations necessary for the transformation of rough diamond into a polished diamond are as follows:
- Cleaving
- Sawing
- Bruting
- Cross Working
- Brillianteering
The transformation of a octahedron rough diamond (top line) and a dodecahedron rough diamond (line below) into a polished diamond.
Cleaving
Not all rough diamonds needs to be cleaved or sawed. Some rough diamond are well formed and can be considered ready to be cut. In order to remove any impurities or irregularities in the diamond, a rough diamond is placed in a quick-drying cement. A sharp groove is then carved into the diamond, using another diamond or a laser, along the plane of weakness. Then, a steel blade is placed in the groove and a sharp blow to the blade is applied spliting the stone. The diamond is then removed from the cement.
Sawing
Sometimes, diamonds have to be cut against a cleavage plane, which cannot be done by cleaving. Using a phosphor-bronze blade rotating at about 15,000.00 rpm, the saw slowly cuts through the diamond.
Lasers are also being used to saw diamonds.
Bruting
This procedure is performed only for diamonds that are to be finished as round, brilliant stones (fancy shaped stone require a different type of preparation).
The diamond is placed in a lathe, and another diamond in the lathe is rubbed against it to create the rough finish of the girdle.
Cross Working
The function of crossworkers is to lay the foundation of the diamond and to follow the instructions to obtain the optimum value for the finished product. Cross-workers can decide to process a diamond, fully aware that the finished product will contain inclusions. On the other hand a decision may be made to improve the quality with a resulting smaller diamond as a finished product. The work is done on a polishing disc driven by an electric motor. The disc is covered with diamond powder. The diamond to be polished is held in a clamp and the facets are polished one by one. Crossworkers do polish 18 facets to a very stringent measurements and angles.
Brillianteering
The function of brillianteers is to cut and polish an extra 40 facets onto the already polished facets done by the cross-workers, in order to create a round brilliant cut diamond with 58 facets that will unlock the full brilliance and fire of light being reflected by the polished diamond.