Diamondology is a science of knowing diamonds (Cuttings, Color, Carat, Clarity, Hardness, …) When selecting a diamond, it's important to know the aspects of each stone. Cut, color, carat and clarity (that called 4Cs.) are among the most common factors, along with various others.
the highest quality diamonds are totally colorless generally, whereas lower quality diamonds can often have a slight yellow tint. Diamond color is measured using the color scale which goes from D (colorless) all the way to Z (light yellow or brown in color).