White diamonds are not all colorless. The spectrum ranges from totally colorless to light yellow. A lettering system from D to Z is used to identify the amount of color present in each diamond, with D awarded only to the rarest, totally colorless diamonds. Diamonds graded D, E or F are considered colorless. Diamonds graded G, H, I or J are considered near colorless. The color will intensify further down the scale. The more colorless a diamond, the more rare it is, therefore, more valuable.