The color of a diamond
refers to its degree of "yellowness." The ideal diamond is completely
colorless, and is therefore the most expensive. The Gemological Institute of America (GIA)
grades color alphabetically from D (totally colorless) to Z (yellow):
For a diamond to be considered "colorless,"
the GIA requires it to be D, E, or F. However,
the D-Z scale is continuous, so the difference between
F and G is very small. The average color for engagement
diamonds in the United States is G to H.
Jewelers and consumers have three tools at their disposal
to judge the color of a given diamond: (1) a "reference set"
of stones, (2) a "colorimeter", and (3) a certificate from
a well-known gemstone laboratory such as GIA or AGS.
Reference Set. A jeweler will compare the diamond in question with a
set of stones of known color (the set is typically comprised
of cubic zirconium!). Then the jeweler will make a qualitative determination
as to the color grading of the stone in question. When judging the color of a
diamond using a reference set, it is crucial to see the diamond unmounted. Ask
the jeweler for a reference set of stones to make the comparisons
yourself. To do this, place the diamond in question next to the reference stones
face down on a white piece of paper. Compare the color of the stones until
you get the best match.
Colorimeter. The second, more precise method, is to use a colorimeter,
an electrical device that measures the optical characteristics of the stone
and reports the color to within 1/3 of a grade. If available, ask to see
the printout from the colorimeter.
GIA or AGS Certificate. The best way to determine the color of a given
stone is to simply look at its accompanying certificate. Reputable diamond certification
labs such as GIA or AGS go through great lengths to ensure the accuracy of their gradings,
employing the latest technology and processes.
Perhaps the most important factor
to consider when selecting color is the type of setting
you plan to use. If you plan to mount the stone
on a platinum or white gold setting, consider a diamond
in the D-G range. Yellow gold will be much more forgiving
to a less than colorless stone. Regardless of the
setting, the diamond will appear yellow if
the color grade is lower than around J.