The process of cutting and polishing gems is called gem cutting or lapidary, while a person who cuts and polishes gems is called a gem cutter or a lapida. The cutting of the diamond includes three series' of operations: splitting (or cleaving), cutting and polishing (which includes setting and polishing the diamond).

The rough diamond is given to the splitter and it is he who determines the future of the stone. He decides how it should be shaped to retain the utmost weight with the most brilliant effect.

From the splitter the diamond passes to the cutter. His expertise lies in giving the stones the definite form which they are to preserve.

After a gemstone is sawed and ground to the desired shape and sanded to remove rough marks left by coarser grits, it is usually polished to a mirror-like finish to aid light reflection from the surface of the stone (or refraction through the stone, in the case of transparent materials).

The natural form of a diamond will determine the shape of the final polished diamond. 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. A standard round brilliant cut has usually 57 or 58 polished facets. Sometimes months, and even years, are required for the perfecting of single stones. African diamonds are said to be particularly hard and difficult to polish; but, in the end, the most hopelessly resistant gem yields to the indefatigability of man. Diamond cutting is a great skill, practiced from generation to generation. The monotonous toil, patience and technical skill inherited and acquired by the workman are at last rewarded by the glitter of the magnificent stone polished to perfection. The traditional diamond cutting and trading centers are based in Antwerp, Mumbai, Tel Aviv, New York and Johannesburg. China and Thailand are more recently developed centers.