The best color or tint is absolutely none. Yet most diamonds appearing colorless have slight tones of yellow or brown. The less color there is the higher the value. The color grading scale below categorizes the light differences between diamonds.
At Barmakian Jewelers, our gemologists will show you similar diamonds with different color gradings side by side in our private diamond viewing rooms. There you can learn about what you prefer for diamond color.
Images from http://www.gia.edu/