When it comes to the 4Cs of diamonds, color, or lack of it, is an especially important characteristic. Diamonds are given letter grades to denote the level of color, starting with the letter D for a flawless, colorless diamond. Why D, and not C, B, or A? The reason we've heard is that when diamonds started being graded for color with this scale, it was decided to start with D, to leave room for the extremely rare possibility that a diamond would be found that was even more flawless than flawless. It hasn't happened yet!

The color grades of D, E and F are the rarest and most colorless. The gradations in color can only be seen by an expert gemologist. The grades G-H are called near colorless and the difference can be seen by a casual observer only when compared to a higher-grade diamond. A stone in this grade category is an excellent value. The grades I-J are also near colorless, but not to the same extent as G-H. These also are an excellent value.

The color grades move up the scale to Z, with an increasing amount of color. These are inferior gem-quality stones and should not be confused with canary or other colored diamonds. Colored diamonds are graded differently than white diamonds and are also highly prized among collectors. They're especially beautiful when combined with white diamonds. Consider that the Hope Diamond, one of the most famous diamonds, is a rich blue color. Out of all colored diamonds, a red diamond is the rarest of all.

The colors in colored diamonds come from impurities between the cells of the crystals, or structural defects. There are many different colors that diamonds can come in, but they're limited to steel gray, white, blue, yellow, orange, red, green, pink to purple, brown, and black