Branch of lapidary art involving the five basic steps in fashioning a diamond: marking, cleaving, sawing, girdling, and faceting. The most popular style is the brilliant cut, a round stone with 58 facets; a round diamond with only 18 facets is known as a single cut. Any other style is known as a fancy cut. Seealso gemstone.
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Diamond cutting is the art, skill and, increasingly, science of changing a diamond from a rough stone into a faceted gem. Cutting diamond requires specialized knowledge, tools, equipment, and techniques because of its extreme hardness.
The first guild of diamond cutters and polishers (diamantaire) was formed 1375 in Nuremberg, Germany, and led to the development of various types of 'Cut'. This has two meanings in relation to diamonds. The first is the shape: round, oval and so on. The second relates to the specific quality of cut within the shape, and the quality and price will vary greatly based on the cut quality. Since diamonds are very hard to cut, special diamond bladed edges are used to cut them. The first major development in diamond cutting came with the "Point Cut" during the latter half of the 14th century. The Point Cut follows the natural shape of an octahedron shaped raw diamond, eliminating waste in the cutting process.
The round brilliant cut and square brilliant cuts are preferred when the crystal is an octahedron, as often two stones may be cut from one such crystal. Oddly shaped crystals, such as macles are more likely to be cut in a fancy cut—that is, a cut other than the round brilliant—which the particular crystal shape lends itself to.
Even with modern techniques, the cutting and polishing of a diamond crystal always results in a dramatic loss of weight; rarely is it less than 50%. Sometimes the cutters compromise and accept lesser proportions and symmetry in order to avoid inclusions or to preserve the weight. Since the per-carat price of a diamond shifts around key milestones (such as 1.00 carat), many one-carat (200 mg) diamonds are the result of compromising Cut quality for Carat weight. Some jewelry experts advise consumers to buy a 0.99 carat (198 mg) diamond for its better price or buy a 1.10 carat (220 mg) diamond for its better cut, avoiding a 1.00 carat (200 mg) diamond, which is more likely to be a poorly cut stone.
Natural green color diamonds most often have merely a surface coloration caused by natural irradiation, which does not extend through the stone. For this reason green diamonds are cut with significant portions of the original rough diamond's surface (naturals) left on the finished gem. It is these naturals that provide the color to the diamond.
Sawing is the usage of a diamond saw or laser to cut the diamond rough into separate pieces.
A simplified round brilliant cut process includes the following stages:
This is just one, although fairly common way of creating a round brilliant cut. The actual process also includes many more stages depending on the size and quality of the rough. For example, bigger stones are first scanned to get the 3-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.