Generally, diamonds range from colorless to a yellow-brownish shade. There are fewer diamonds that have less color making them rise in value, but there are also some stones called fancies that may be worth more than a colorless stone. The most common of the fancies is yellow, but remember that diamonds may come in many colors including pink, blue and black. The standard grading scale for diamonds begins at D (the colorless diamonds) and ends at Z ( the diamonds with a yellow or brown shade). Below is an example of the scale provided by GIA and how each letter represents a range of tones.
Of the four factors that are used to grade a diamond, color is the hardest to grade. This problem exists only because humans grade stones on a basis of opinion, and sometimes the opinion is skewed in their favor. If the diamond has a GIA certification provided with it than color grading isn’t an issue because it is provided by a reputable source. In all honesty, a stone graded between J and H is a very impressive stone, and practically colorless to the inexperienced eye, so worrying about getting a stone as close to D as possible shouldn’t be of great concern.