Gemological Institute


Diamond is the hardest known natural material and the third-hardest known material after aggregated diamond nanorods and ultrahigh frequency. Its hardness and high dispersion of light make it useful for industrial applications and jewelry.

The 5Cs and things to know about Diamonds


The cut of a diamond refers to its proportions. Of the 5cs,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 rough. Whatever the shape, a well-cut diamond is better able to reflect light. A diamonds ability to reflect light determines its display of fire and brilliance.


The clarity of a diamond refers to how clear, or “clean” the diamond is. The more “clean” the diamond, the higher the price. Most diamonds have “imperfections” in them. The clarity scale is a measure of the severity of those imperfections or “inclusions” as it is known in the trade.

Both of these distinguishable features together are called clarity characteristics. A clarity grade is determined by the relative absence of clarity characteristics.

The following is the GIA Diamond clarity-scale:


Shows no inclusions or blemishes of any sort under 10X magnification when observed by an experienced grader



Has no inclusions when examined by an experienced grader using 10X magnification, but will have some minor blemishes



Contains minute inclusions that are difficult even for experienced graders to see under 10X magnification.



Contains minute inclusions such as small crystals, clouds, or feathers when observed with effort under 10X magnification.



Contains inclusions (clouds, included crystals, knots, cavities, and feathers) that are noticeable to an experienced grader under 10X magnification.



Contains inclusions (possibly large feathers or large included crystals) that are obvious under 10X magnification and may affect transparency and brilliance.



A diamonds color is another indicator of its value. The closer a stone is to colorless in other words, the less color that is apparent the more value it has. The diamonds value drops at the first sign of yellow or brown hues.

The best color is no color. Diamonds allow light to be reflected and dispersed as a rainbow of color. This light dispersion has no effect on the technical grading of color. The absolute finest colorless stone carries a D rating, descending through the alphabet to Z, designating a diamond of light yellow or brown.

These gradations are so minute and precise that discerning a single grade (even by an expert) under less than ideal laboratory conditions is virtually impossible. It is often surprising to learn that diamonds also occur by rare accidents of nature in shades of pink, blue, green, amber or even red. These rare occurring colors are referred to as fancies and are evaluated by a different set of color standards.

The most respected system used today for evaluating diamond color was developed by the Gemological Institute of America, (GIA).



The carat weight measures the mass of a diamond. One carat is defined as 200 milligrams (about 0.007 ounce avoirdupois). The point unit-equal to one one-hundredth of a carat (0.01 carat, or 2 mg)-is commonly used for diamonds of less than one carat. 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.

The price per carat does not increase smoothly with increasing size. Instead, there are sharp jumps around milestone carat weights, as demand is much higher for diamonds weighing just more than a milestone than for those weighing just less.

As an example, a 0.95 carat diamond may have a significantly lower price per carat than a comparable 1.05 carat diamond, because of differences in demand.


Round– This is by far the most popular diamond shape and also the most optically brilliant

Oval – This cut makes the most use of the sparkle of a round-brilliant cut, and combines this with an elongated outline which is particularly flattering on the hand.

Princess – This has become particularly popular over the last few years – developed in 1970, the Princess is now second only to the round in popularity.

Emerald -This is considered among the most classic of diamond shapes

Radiant -The Radiant Cut Diamond is a straight-edged rectangular or square stone with cut corners

Heart – The Heart Shaped Brilliant bears some similarity to the Pear Shape, except that there is a cleft at the top.

Marquise – The Marquise Cut takes its name from a legend relating to the Marquise of Pompadour.

Pear – The Pear Shaped Brilliant Diamond combines the shape of Round brilliant and Marquise cut.