Cut | Color | Clarity | Carat Weight | Other Aspects

Of all the criteria used to assess diamonds, cut is the most obvious one to the naked eye. The cut of a diamond is what gives a stone its brilliance and sparkle. But don’t confuse cut with shape. To a gemologist, the term cut refers to how efficiently light is transmitted through a gem, based on an ideal set of proportions, as shown here.



Unfortunately, cut is one of the most overlooked qualities of diamonds. Of the recognized laboratory diamond certificates, only the American Gem Society Report assigns a specific cut grade to a brilliant-cut stone. Like all A.G.S. grading standards, the scale is divided between 0 and 10, with 0 being the best.

Some on-line merchants offer superficial grading information about the cut of their diamonds. Terms such as "very good" and "excellent" are subjective and should be avoided. Diamonds may be described by a seller as "ideal" without meeting A.G.S. standards for an ideal stone.

How do such practices affect consumers? If you compare two stones that are equal in all grading areas except for cut, the stone with the superior cut could cost as much as forty percent more than the lesser-cut diamond. A trained gemologist considers at least eight factors when evaluating cut, including a stone's major proportions, polish, and symmetry. He or she can explain the variation in cut grades — and the effect of the cut grading on the value of each diamond — so that shoppers can make informed choices.

A trained gemologist considers at least eight factors when evaluating cut, including a stone's major proportions, polish, and symmetry.