Almost all diamonds possess some degree of body color, usually yellow or brown. A small percentage of diamonds are colorless, and an even smaller number possess body color so strong that they are classified as "fancy colors".

Color is graded on the scale developed by the GIA and is almost universally used today to classify diamonds in the world market. The "normal range" of this alphabetic scale starts at "D" (colorless) and runs through "Z" (light yellow or brown). Colorless stones are rarer and more valuable than stones with body color in the normal range. However, diamonds graded as fancy are analyzed differently and can be extremely valuable.

It is helpful to think of the scale in terms of grade ranges: D,E,F are considered colorless, G,H,I,J are near-colorless and lower grades are slightly tinted to lightly tinted.

Differences between color grades are extremely subtle. Professional diamond grading is done in controlled lighting conditions with the stones in table-down position, with the grader looking through the girdle of the stone in order to see the slight differences in body color. Diamonds in the near-colorless to colorless range will appear white or colorless to the eye when viewed through the table.

In addition to the increased rarity and value of colorless stones, body color also impacts the quality of light emanating from a diamond. Body color acts as a sort of filter that diminishes to an extent the pure nature of light returning to the eye. Colorless diamonds that are well-cut exhibit the best spectral display or "fire."

Although lower colors can still be very beautiful Gem Diamond Company prefers to sell only diamonds of J color and above.

Flourescence

Flourescence, also known as photoluminescence, is a property in some diamonds that causes them to glow when exposed to ultraviolet light. The effect is rarely noticeable under normal circumstances and is chiefly an identifying characteristic of a given diamond. In many cases flourescence is a benefit, helping lower colors to appear whiter, but in rare cases it is detrimental, causing the stone to look slightly foggy in certain light.

Practical advice:

While colorless stones are rarer and cost more, near-colorless stones will look essentially the same to the eye when set in jewelry. Choosing a GHIJ color instead of one in the DEF range will enable you to get a larger diamond for the money, without a substantial compromise in performance or beauty. If the diamond is to be set in white gold or platinum, aim a little higher on the scale than you would if setting it in yellow gold. Yellow gold disguises body color whereas white metal reveals it.

Blue flourescense can add to eye appeal of near-colorless diamonds and therefore be a benefit. Very strong fluorescence will not enhance colorless stones and may detract from their beauty and value.