Stones are graded by color and given designations dependent on how far they deviate from the purest white. Colorless stones are graded D. Color grading continues down through the alphabet, with each letter designating a more yellowish tint. The best way to see the true color of a diamond is by looking at it against a white surface. Although the great majority of diamonds come in shades of white, the gems also come in a spectrum of majestic colors, from red and canary yellow to blue, green and brown. These colorful diamonds, known as fancies, are valued for their depth of color, just as white diamonds are valued for their lack of color.
Colorless stones are expensive.
The color difference only really shows when compared side by side with a different stone. Since color grading is so difficult, not all jewelers are accurate in their diamond grading. A carat is equal to one fifth of a gram. For some consumers, a diamond's size, expressed by the carat weight seems to be the most important feature. While size matters, a large diamond is not necessarily equivalent to a beautiful diamond.