The four C's
The weight of a diamond is expressed in carats, derived from “keration,” which is the Greek name for the pod of the carob tree, whose individual seeds weigh approximately 0.2 grams, which equals 1 carat. Carats are subdivided into points and there are 100 points in one carat.
Pure diamonds are extremely rare, and almost all contain impurities or “inclusions.” These are traces of non-diamond materials that were trapped in the mineral during the stone’s formation. Typically, many inclusions are removed during the cleaving, sawing, cutting and polishing of a diamond.
most diamonds are referred to as “colourless,” which ranges from absolutely colourless to yellowish. A small percentage of diamonds display vivid colours, including yellow, red, pink, green, brown and black. These are referred to as “fancy coloured” diamonds.
The quality of a polished diamond’s cut, or the “make,” as diamond dealers often say, decides how the light entering the stone will react, and consequently how brilliant the stone will appear. Diamond cutters do their utmost to fashion each stone according to an exact mathematical formula, in which the facets of the diamond are polished at precise angles to one another. A Belgian mathematician, Marcel Tolkowsky, introduced the most famous formula for the 57-facet round brilliant stone in 1919.