|Acting as a prism, a diamond can divide light into a spectrum of colors and reflect this light as colorful flashes called fire. Just as when looking through colored glass, color in a diamond will act as a filter, and will diminish the spectrum of color emitted. The less color in a diamond, the more colorful the fire, and the better the color grade.|
|Less Equals More|
|Diamonds composed of pure carbon are colorless. But such stones are quite rare. Most diamonds contain varying degrees of nitrogen, boron or hydrogen, any of which impart color. The majority of diamonds exude barely perceptible shades of yellow or brown, which are attributed to traces of nitrogen.|
|Understanding Diamond Color Grading|
|Many systems have been used to grade diamond color. To eliminate confusion, the Gemological Institute of America (GIA) introduced a color grading system in the 1950s that is used today by the entire diamond industry. The scale begins at D (colorless) and ends at Z (light yellow). The scale starts at D because that letter had not been used previously to classify color.|
|How Color Grading Is Performed?|
|Diamond color is difficult to discern when a diamond is viewed face-up. Therefore, the grader turns the diamond facedown against a pure white surface under carefully controlled light. The diamond grader compares the diamond to a so-called master stone to determine color. A master stone is a diamond of a predetermined color that is used for comparison.|
|What Color Grade Is Best?|
|For the purist, look for a colorless diamond with a grade of D-F and a fluorescence rating of faint, inert, none, or negligible.
For an excellent value in a diamond with no noticeable color to the unaided eye, look for a near-colorless grade of G-I, and a fluorescence grade of medium or strong blue.
Or, if you'd rather not compromise on color but would like to stay on budget, choose a diamond with a good cut, SI1-SI2 clarity, and consider going with a strong fluorescence. It will still be beautiful to the unaided eye and you may prefer the unique effect of a strong fluorescence.