White diamonds were long thought of as the most beautiful stones. However, that was because there was very little output of colored diamonds. The color of a diamond is determined completely by nature. A diamond that is close to being colorless is more valuable and beautiful because a diamond acts like a prism, dividing light into a spectrum and reflecting it back to your eye in flashes of fire. Color can act as a filter, reducing the fire that gives a diamond its beauty and brilliance. Diamond colors range from D to Z. Fine diamonds fall into the range from color grade D to I. Color grades D, E and F are considered colorless, making them rare.