The second most important grading aspect when buying or selling diamonds is that of color. Diamonds are graded based on their overall body color, on a scale developed by the GIA. This scale runs from 'D' to 'Z'. As you will note in the images the difference between any two colors can be very, very faint. Therefore it is required to use a Master Color Grading set of diamonds, which have been pre-graded to known color grades on the scale. Thereby allowing the gemologist to accurately grade a diamond's color by comparing it to other diamonds of known color. Of course, it is required that the Mater Color Grading diamonds be graded by a qualified gemological laboratory to insure accuracy of the master grading set. There are some new instruments on the market today which electronically color grade diamonds. However, due to variations in calibration, and the impact that fluorescence has on these machines, they should only be used in conjunction with a Master Color Grading set to insure the most accurate grading.
It should be noted that to achieve the highest degree of accuracy diamonds must be color graded loose and with the proper equipment. The stones should be upside down to provide the best viewing of the crystal color. And a proper "North Light" source should be employed. And any diamond grade offered on a stone while still in its mounting should be noted as being provisional based on the limitations of grading while the diamond was in the mounting. More than one diamond has looked yellowish inside an 18kt. yellow gold mounting, only to be found as colorless when unmounted. So be careful when you are buying....or selling.
D-E-F
The colors of D-E-F are known as the colorless grades. The color grade of 'D' is reserved for larger diamonds whose colors can be more accurately graded due to a larger stone to work with. Diamonds of sizes under .50 carat usually will get a top grade of 'F' due to the greater difficulty in grading a small diamond to the exact color grade.
G-H-I
These are known as the 'face white' or "face up colorless" grades. Since these diamonds will appear colorless when viewed through the 'face up' position or through the table, but when turned upside down for proper grading the stone will show a slight tint of color. This is due to the brilliance of the stone masking this very slight tint when viewed through the table. (see Importance of Proportioning above)
J-K-L
Much beligned by jewelers and consumers, this grading range can offer some very nice diamonds if they are proportioned properly. A well cut diamond of the K-L color range will still appear mostly colorless and can save the consumer a good deal of money over a color grade of a higher range. Again, the cut is the key to keeping the stones of slight tint beautiful.
M-Z
The lower colors from 'M' through 'Z' will have a continuously increasing amount of yellow tint. Ranging through the off colors and ending at the end of the scale beyond which diamonds are considered to have a fancy yellow color.
Fancy Colors
Diamonds have been found in just about every color of the rainbow. From the very rare red to the sometimes radioactive greens. The natural fancy colors will be quite expensive. While some of the treated diamonds will cost less than lower quality off color diamonds. Either way there is much more about diamond color that we could discuss here. Perhaps we will continue with this topic in the near future. If you have specific questions about diamond colors and color grading send it to me and I will get the answer for you.
