Grades in the color of diamonds range from D-Z. D is colorless and of the highest quality. E and F are also graded as colorless. G, H, I and J are near colorless. Diamonds graded K, L, and M will have obvious hints of color and as the scale gets to P you might find subtle changes in hue and tone. The exceptions to the rule are "Fancy" diamonds in well-highlighted colors that include pink, blue, red, green, and canary yellow. These are particularly rare and much sought after.