The Gemological Instituted of America's color grading chart is the diamond industry standard. The chart is available from most jewelry stores, diamond brokers and valuation companies, including Lumera Diamonds, DiamondDeals.com and Diamonds.pro. The GIA scale chart rates the clarity of a diamond on a scale from D to Z.
The GIA color chart scale rates a white diamond's color in five categories, including colorless, near colorless, faint, very light and light. The color differences are very subtle but translate to a significant difference in quality and price. Fancy colored diamonds, such as yellows, pinks and blues, exist but are graded on a different scale.