When a gemstone is desired to be used in jewelry, it is cut depending on the size and shape of the rough stone, as well as the desired piece of jewelry to be made. As a rule of thumb, a cut gemstone will reduce the mass (described in the carat) by about 50 percent.
There are several techniques available to work with gemstones; among them are sawing, grinding, sanding, lapping, polishing, grilling, and tumbling. Very often, the location of the inclusions in a rough stone will determine the type of shape to which a gemstone may be cut.
Types of cut
Based on the optical impression of the cu gemstones, there main groups of cut are classified.
1. Faceted cut - most faceted cut can be divided into three basic type - Brilliant cuts, Triangular facets and Radial pattern
2. Plain cut - the plain cut like cabochon serves mainly for agate and other opaque gemstones.
3. Mixed cut - is a combination of the faceted and plain cut. On the upper or lower part, the gemstone carries facets while other part is plain or vice versa.
Forms of cutting
An abundance of forms is derived from the basic types of the gemstone cuts. They can be round, oval, square, rectangular, triangular, pear, heart and new forms are created by designers.