The four characteristics are carat, clarity, color, and cut.  Wholesale market can use the four C's of a diamond to establish an expected price range. More detailed information from within each characteristic can be used to determine actual market value for individual stones.

 

Carat is the unit of weight for the diamond. One carat is defined as exactly 200 milligrams (about 0.007 ounce). 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. Value per carat increases exponentially in relation to carat weight, because larger rough diamonds occur less frequently.

 

Clarity describes the clearness or purity of a diamond. Internal defects of a diamond are called inclusions. Inclusions may be crystals of a foreign material or another diamond crystal, or structural imperfections such as tiny cracks that can appear whitish or cloudy. The number, size, color, relative location, orientation, and visibility of inclusions can all affect the relative clarity of a diamond. Diamonds become increasingly rare when considering higher clarity gradings.

 

Color describes the amount of color the diamond contains. A chemically pure and structurally perfect diamond is perfectly transparent with no color. However, in reality almost no gem-sized natural diamonds are absolutely perfect. The color of a diamond may be affected by chemical impurities and/or structural defects in the crystal lattice. Depending on the hue and intensity of a diamond's coloration, a diamond's color can either detract from or enhance its value. For example, most white diamonds are discounted in price as more yellow hue is detectable, while intense pink or blue diamonds (such as the Hope Diamond) can be dramatically more valuable.

 

Cut ensures that a given stone has maximum brilliance and sparkle which would not be the case were the stone cut for weight alone. The cut of a diamond describes the manner in which a diamond has been shaped and polished from its beginning form as a rough stone to its final gem proportions. The cut of a diamond describes the quality of workmanship and the angles to which a diamond is cut.