If you've ever tried to match the colors on the rack in a store with something in your closet at home, you know how deceptive color can be. Distinguishing color is not as easy as it seems at first glance. With diamonds, even small differences in color can make a big difference.

A colorless diamond is graced with that glorious display of light and prismatic colors for which diamonds are so highly prized. The presence of color then goes from barely discernable near colorless to light yellow or brown. Beyond a certain point, or with other colors such as green or red, a diamond is considered a fancy color.

Unless a diamond is a fancy color, the AGS Color Grading System places it on a 0 to 10 scale, to show the range from the rarer colorless diamonds to those diamonds with varying tinges of yellow or brown.

To find an accurate color grade, an AGS member jeweler compares each stone to a set of Masterstones which have been graded according to AGS standards. It is part of an AGS member store's commitment to maintain a minimum of three, and frequently five, masterstones specifically for grading purposes.

Masterstones are diamonds, not cubic zirconia (CZ). Ask any jeweler to show you the Masterstone Set by which their diamonds are color graded. Maybe you won't be able to discern the fine color differentiations between the stones, but you will certainly get a glimpse of that store's commitment to professionalism. If they take the trouble and bear the expense of maintaining a set of Masterstones, you get a sense of their dedication.