THE 4C'S OF DIAMOND QUALITY
Carat is the unit of weight for the diamond. A carat is further subdivided in 100 points ( 0.01 carat = l point ). One carat is equal to 0.20 grams. Value per carat increases with carat size, because larger rough diamonds occur less frequently. In other words, 2 half-carat diamonds taken together will not cost as much as 1 one-carat diamond, as the one-carat stone is more rare.
Clarity describes the clearness or purity of a diamond. This is determined by the number, size, nature, and location of the internal (inclusions) and external (blemishes) imperfections.
Color describes the amount of color the diamond contains. This can range from colorless to yellow with slight tints of yellow, gray or brown. Colors can also range from intense yellow to brown, blue, green, pink and red. These fancy colors are rare and therefore more valuable.
Cut refers to the proportions, finish, symmetry, and polish of the diamond. These factors determine the fire and brilliance of a diamond. Well-cut diamonds sell at a premium and poorly cut diamonds sell at discounted prices. With the advent of technology, the cut of the diamond can be determined through the use of the Dia-Mension system, a computerized system which takes accurate measurements and proportions of a diamond in seconds, in addition to the standard millimeter gauge.
As an example, a round brilliant cut has 58 facets. Since the quality of the cut is directly responsible for the stone's beauty, the precision with which the facets are arranged is of prime importance. They determine the amount of light reflected to the eye, called brilliance.