Cut refers to the proportions, finish, symmetry and polish in transforming a rough diamond into a polished diamond. A well cut diamond will internally reflect light from one mirror like facet to another and disperse and reflect it through the top of the stone. This results in a display of brilliance and fire. Diamonds that are cut too shallow or too deep leak or lose light through the side or bottom, resulting in less brilliance and ultimately, value.
Cut is the only one of the 4Cs that is influenced by the human hand. Diamond cutting requires great skill. The diamond cutter must polish tiny surfaces known as facets onto the rough diamond. This process is what creates the crown, culet, table, girdle and pavilion of the diamond. The facets when arranged in precise proportions, will maximize brilliance and sparkle.
Many people also refer cut to the shape of a diamond for example - round, heart, princess, oval, emerald, pear, marquise, radiant, trillion, asscher and cushion.
Cut and cutting style work in harmony to create a diamond's brilliance. Three basic cuttings styles are: brilliant-cut (round); mixed-cut (princess) and step-cut (emerald).
A round diamond is symmetrical and capable of reflecting nearly all the light that enters, it is the most brilliant of all the diamond shapes. Non-round shapes, also known as "fancy shapes" have their own guidelines to be considered well cut. As an example, a round brilliant cut, which has 58 faucets. Since the quality of the cut is directly responsible for the stone's beauty, the precision with which the facets are arranged is of prime importance. They determine the amount of light reflected to the eye called brilliance.
Expert diamond cutters over the years have created specialty cuts with spectacular fire and brilliance. Examples are kites, stars, and half moons. Other specialty diamonds might look like a standard round, when in fact they have more facets then the standard 58.
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