A diamond appraisal is used to determine the dollar value of a specific gem. Loose diamonds that are bought and sold by jewelry wholesalers for the wholesale diamond jewelry market are subject to the . Diamond appraisal uses four main criteria - known as the "Four C's" - in order to evaluate loose diamonds and determine fair market prices of such precious stones.

The Four C's

The first three criteria are:

- carat: the size of the stone in terms of weight and mass. A modern carat is equal to 1/142nd of an ounce (i.e., a 142-carat diamond weighs one ounce).

- clarity: the diamond's degree of "flawlessness." Virtually all loose diamonds have tiny imperfections, but these are not usually visible to the unaided eye. Virtually flawless diamonds are graded FL. Diamonds with visible imperfections (called "inclusions") are rated "I," and those with "slight" inclusions are rated "S."

- color : For a gem that is technically "colorless," diamonds come in an astonishing number of colors, ranging from pure white to dark brown. Each color is rated from one to seven, with seven denoting the deepest, most vivid colors. Diamond color is caused by chemical reactions with other elements; some diamonds today are irradiated as well in order to increase the intensity of color.

These are objective, quantifiable and easily measured characteristics that are usually determined by a gemologist.

The fourth "C," cut, is more difficult to evaluate. Thanks to technological advances that now allow professional diamond cutters to use lasers and computer aided design, there are well over 250 different diamond cuts available. Most gem-grade diamonds have 57 facets; the way these are done will have a great affect on the results of the diamond appraisal.

Where to Get a Diamond Appraisal

For reasons that should be obvious, any diamond of which you are considering the purchase should receive a diamond appraisal by . They should be willing to have such diamonds shipped to a lab for an appraisal, and you should not pay for and take delivery of such and agree to the purchase price.

One thing to keep in mind - especially in these days of economic volatility and turmoil - is that the value of diamonds can change considerably within relatively short periods of time. A diamond appraisal is important for the determination of fair market value, but the exact purchase price will depend on current market conditions.