Levels of Diamond Quality

• Buying a diamond can be a daunting experience. It would be unwise, as well as impossible, to determine its value by viewing it with the naked eye. Before purchasing a diamond, you should have some knowledge about the diamond's quality and ratings. The Gemological Institute of America developed a system for grading, evaluating and measuring diamond quality that is used worldwide. All diamonds share four characteristics that allow you to compare and evaluate them.

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Color

• The quality and price of a diamond is often determined by its lack of color. In other words, the less color a diamond has, the higher its value. The Gemological Institute of America developed the first color-grading scale for diamonds and it is used throughout the diamond industry. The scale begins with the letter grade "D" -- meaning colorless -- and extends to the letter "Z," meaning light yellow or brown. A diamond is compared to a set of diamonds, whose color has already been determined, to determine its color.

Carat

• A carat refers to the standard unit of weight of a diamond or other gemstone. One carat is equal to 0.2 grams. For diamonds weighing under one carat, each carat is divided into 100 points. For instance, a 0.25-carat stone has 25 points. If a diamond's weight is greater than one carat, it is described in carats using decimal point -- for example, a 1.50 carat diamond. Because larger diamonds are rarer and more expensive than smaller diamonds, precise weight must be determined.

  As a side note, "carat" is not the same as "karat." Karat, such as "14K gold," refers to the amount of gold in an item.

Clarity

• Gemologists refer to imperfections found in diamonds as inclusions, which are in the interior structure of the stone, and blemishes, which are flaws found on the surface. Nearly all diamonds will have some inclusions and blemishes; flawless diamonds are extremely rare. Diamonds are rated for clarity using the Gemological Institute of America Clarity Scale, which ranges from "Flawless" to three degrees of "Included," meaning the gem has internal flaws that are visible under only a 10--- magnification and may affect its transparency and brilliance. Multiple factors are considered when determining the clarity rating, such as size, nature, position, color, and number of clarity characteristics visible under 10--- magnification. Jewelers also use the Clarity Scale to determine the authenticity of a diamond.

Cut

• The fire and brilliance of a diamond depends more on the cut than anything else. There are many shapes or designs of diamonds: round or "brilliant," princess, marquise, pear, oval, emerald, heart and square. As far as value, the cut refers to a diamond's proportions, symmetry and polish. It must be cut precisely by a master craftsman to maximize its brilliance. Diamonds are graded from excellent to poor cut grade.