The Quality of Diamonds – The 4 C’s
Cut
The cut of a diamond refers to its proportions. Of the 4C‘s, the cut is the aspect most directly influenced by man. The other three are dictated by nature. Quite often the cut of a diamond is confused with its shape. Diamonds are cut into various shapes depending upon the original form of the uncut diamond, which is referred to as “rough.” Whatever the shape, a well-cut diamond is better able to reflect light.
A diamond‘s ability to reflect light determines its display of fire and brilliance. Diamonds are usually cut with 58 facets, or separate flat surfaces. These facets follow a mathematical formula and are placed at precise angles in relation to each other. This relationship is designed to maximize the amount of light reflected through the diamond and to increase its beauty.
Color
The best color is no color. Diamonds allow light to be reflected and dispersed as a rainbow of color. This light dispersion, or color flash, has no effect on the technical grading of color. The absolute finest colorless stone carries a D rating, descending through each letter of the alphabet to Z, designating a diamond of light yellow, brown, or gray.
Why does the GIA color grading system start at D?
Before GIA developed the D-Z Color Grading Scale, a variety of other systems were loosely applied. These included letters of the alphabet (A, B and C, with multiple A’s for the best stones), Arabic (0, 1, 2, 3) and Roman (I, II, III) numerals, and descriptions such as “gem blue” or “blue white.” The result of all these grading systems was inconsistency and inaccuracy. Because the creators of the GIA Color Scale wanted to start fresh, without any association with earlier systems, they chose to start with the letter D—a letter grade normally not associated with top quality.
Clarity
Almost all diamonds contain very tiny natural birthmarks known as inclusions. To determine a diamond‘s clarity, an expert views it under 10 power magnification. In addition to internal inclusions, surface irregularities are referred to as blemishes. These two categories of imperfections-inclusions (internal) and blemishes (external)-make up clarity. The fewer the imperfections, the rarer and more valuable the diamond. Many inclusions are not discernable to the naked eye and require magnification to become apparent. A laboratory-certified clarity rating of SI2 represents the point at which inclusions are technically not apparent to the average naked eye.
Carat Weight
Most people compare carat weight to size. The larger the diamond the more it weighs. The weight of a diamond is expressed in carats. The word carat originated from the carob tree or Ceratonia siliqua. The tiny seeds of this tree are well known for their uniformity and consistent weight. Traditionally diamonds and gemstones were weighed against these seeds until the system was standardized, and one carat was fixed at 0.2 grams.
Diamond Shapes
It is important to distinguish between cut and shape. The cut — brilliant, step or mixed — is the arrangement of facets and determines the diamond’s brilliance. Shape is the contour into which the diamond is cut.
Colored Diamonds
Rare and very expensive, natural colored or “fancy” colored diamonds reflect the colors of the rainbow. Yellow is the most common colored diamond, while pink, red, blue and green diamonds are extremely rare. Fancy color diamonds are cut to maximize color, not clarity. Of the 4C’s, color is the most important criterion for these stones. Generally, the higher the saturation of color, the more valuable the stone.
