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GIA Scales GIA
Diamond D-Z Color Scale
COLOR
Though diamonds come in a wide range of colors, colorless diamonds have traditionally been considered the most valuable. Most diamonds are graded on a scale using the letters of the alphabet, from D (colorless), the best grade, through Z (a light yellow).
It is difficult for the untrained eye to notice such variations in color unless stones are being compared side by side. The comparatively rare colored diamonds are known as fancy-colored and are also quite valuable. They range in hue from the more common yellow (also graded Z+ on the alphabetic scale) to pink, blue, green, red, and even black and white.
Diamonds that are graded D, E, and F tend to be the most expensive because of their rarity. However, any diamond you buy should have a good balance of cut, color, and clarity, so as to impart the most brilliance and dazzle possible.
The less color a diamond posesses, the more valuable
it becomes because of rarity. Color in a diamond has value only when it
reaches the point of saturation where it becomes rare or if the color
(hue) itself is rare. These rare colors are called fancy colors. In 1987
Sotheby's auctioned an approximately .95 ct. pink to purplish natural
fancy color diamond and received more than $800,000 because of rarity.
In the diamonds that we see in the trade, though,
most are near colorless to light yellowish. There are only about 25
impurity elements that effect diamond. In fact, 99.95% of all diamond is
pure carbon.
Some causes of diamond color are as follows:
- nitrogen...yellow
- boron...blue
- crystal irregularities...pinks, browns and reds
- natural radiation...green
About 50% of all diamonds are fluorescent. Some even
glow. This fluorescense is caused by the reaction between the light's
energy and the diamond's atoms. Diamonds that fluoresce usually do so in
blue. Diamonds that fluoresce very strongly may have an oily appearance.
Fluorescence should be disclosed and explained when a diamond is being
shown. Remember slight to moderate fluorescence could be a means of
identification.
To grade color, gemologists use master stones
(stones graded and recorded at the GIA gem trade lab), white light and
proper procedures.
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Jewelry at Auction -
Glossary of terms
