In ancient times, jewelers could not do faceting, they just polished crystals. Craftsmen gradually came to the conclusion that the grinding stone can be given a rounded shape. In fact, it was the beginning of the formation of the art of cut. When the whole stone or attach the top of a rounded shape, it turns cabochon. Currently, this method is used for cutting machining of opaque, translucent and stellate stones. Stellate called stones which when cut cabochon exhibit an optical effect in the form of stars light rays with different amounts. Basically, it's rubies and sapphires, but the effect may occur in the quartz, moonstone, citrine and some other minerals.
Currently, for treatment of most rocks using special saws coated diamond grit. Because of its hardness, diamond dust easily handles any material. There is special equipment with programming, but the work it requires special knowledge and experience, as the cutter itself must determine how to cut the number and arrangement of faces that are most appropriate for each individual stone.
After closure of cut stone can lose up to half of its original weight, but its cost grows while several times.
Diamonds often have internal defects, so they are carefully inspected prior to treatment and then separated into pieces so as to extract the maximum amount of high-quality pieces. For the separation using diamond saw or a laser beam.
The next stage of processing diamonds - friction. Stone "wipes" diamond emery and shall be given a preliminary form. Then selects the appropriate form cutter cut. For diamonds are usually used the same name - a diamond - cut. With her top platform in the form of a regular polygon is surrounded facets located at different levels. Also apply step-cut (the faces of different layers are arranged one above the other) and Diamond cut (on flat ground located triangular faces, converging at the top, used for small crystals).
Already in the twentieth century, a method was developed cut "Princess", which allows to achieve total internal reflection of light rays and causing the enchanting play even small diamonds.
Polishing itself is produced by grinding with a change in tilt angle to obtain the desired facets.
The most common ways to cut are shown in the following figure.
For a darker color in gems used thermal treatment or radiation exposure. The latter method is only used in professional laboratories, as it requires very precise calculations to radiation is not delayed in stone.
In the presence of minor defects on the surface of the cut stone mask their special structures on the basis of wax and oil, cracks sometimes filled with lead glass.
After all these labor-intensive operations is born a real gem - a joint work of art of nature and man.