Diamond Color Rating System

The GIA color rating system has been established using alphabetical nomenclature. The stones are rated from pure (totally colorless) down through a sliding scale to yellow, which is the least valuable stone. The GIA color rating system starts with the letter D and progresses through the alphabet as shown below to Z, which would be very yellow.

• D E F : Colorless
• G H I J : Near Colorless
• K L : Faint
• M : Yellow-White
• N O : Very Light Yellow
• P : Light Yellow
• Q : Yellow
• R S T U : Light
• V : Yellow or Fancy
• W : Fancy
• X Y Z : Yellow

After the letter Z, indicators are used to suggest the stone is more valuable because of its hue; i.e., a fancy color. As you can see from the above chart, D, E and F stones are considered completely colorless. G, H, I and J are near colorless stones and take a lot of practice for the amateur to see any color at all, while after J the stones begin to pick up a small tint of yellow that is noticeable to practiced gemologists.

To correctly grade a gemstone, the stone must be loose, not in a setting, should be on a perfectly white background, should have a white gem quality temperature light and should be viewed from the rear of the stone. In other words, the stone should be upside down Iying on its table. It is also extremely helpful to have stones of known color grades nearby for active comparison.

Never attempt to judge the color of a diamond when it is set in any kind of setting, be it earring, ring, or whatever as it is strictly impossible to judge the color of a mounted stone that is taking on hues and tints from the mounting itself.

Color is a very important consideration in choosing investment quality diamonds and, in fact, the differences in large sizes such as one carat and over from a D to an E color (again these are the top rated stones and are both considered colorless to the naked eye) can be double the price between these two grades.