Diamond Education


Carat Weight

The weight of the diamond is measured in carats. One carat is divided into 100 “points”, so a diamond of 75 points weighs .75 carats. Carat weight is easy to determine, however two diamonds of equal weight can have very unequal value. All else being equal, the price per carat increases with carat weight, since larger diamonds are both rarer and more desirable for use as gemstones. Bigger is not necessarily better. In addition to size, the value of a diamond varies depending on cut, color and clarity.


Clarity is a term used to describe the absence or presence of flaws inside or on the surface of a diamond. Internal imperfections are called inclusions, and surface defects are called blemishes. A clarity grade is assigned based on the overall appearance of the stone under 10x magnification. Most inclusions that are present in gem-quality diamonds do not affect the diamonds’ performance or structural integrity. However, the fewer and smaller the inclusions, the less likely it is to interfere with the passage of light through the diamond. Minor inclusions or blemishes are useful, as they can be used as unique identifying marks or fingerprints. Diamonds with higher clarity grades are more desired, with the exceedingly rare “flawless” graded diamond valued at the highest price.


A chemically pure and structurally flawless diamond is perfectly transparent with no hue, or color. Diamonds occur in a variety of colors; steel gray, white, blue, yellow, orange, red, green, pink to purple, brown, and black. Colored diamonds contain impurities or structural defects that cause the coloration. Depending on the hue and intensity of a diamond’s coloration, a diamond’s color can either detract from or enhance its graded value. Out of all colored diamonds, red diamonds are the rarest of all.


Diamonds are cut into a number of shapes, depending on the nature of the rough stone. When cut to good proportions, the diamond is better able to reflect light, creating more scintillation, more sparkle. New technology, notably laser cutting and computer-aided design has enabled the development of cuts whose complexity, optical performance, and waste reduction were previously unthinkable. Polish and symmetry are two important aspects of the cut. The polish describes the smoothness of the diamond’s facets, and the symmetry refers to alignment of the facets. With poor polish, the surface of a facet can be dulled, and may create blurred or dulled sparkle. It may constantly look like it needs to be cleaned. With poor symmetry, light can be misdirected as it enters and exits the diamond.