A diamond ring must be appraised by a professional jeweler or appraiser to know its value. Those who are trained in determining the value of jewelry often specialize in a certain type of jewelry.
Some appraisers are exclusively involved in the business of rating diamonds. Others also buy and sell them. In addition, pawnbrokers are able to determine the value of lower-quality diamonds. Diamond quality is based on four criteria: color, clarity, cut and weight. The most valuable diamonds are clear and colorless with no visible blemishes. The quality of the cut impacts how well a diamond reflects light. Diamonds are weighed in carats, and one carat equals 200 milligrams.