Diamond type
Diamond type is a method of scientifically classifying diamonds by the level and type of their chemical impurities. Diamonds are separated into four types: Type Ia, Type Ib, Type IIa, and Type IIb. The impurities measured are at the atomic level within the crystal lattice of carbon atoms and so, unlike inclusions, require an infrared spectrometer to detect.
Diamond color
The majority of diamonds that are mined are in a range of pale yellow or brown color that is termed the "normal color range". Diamonds that are of intense yellow or brown, or any other color are called "fancy color" diamonds. Diamonds that are of the very highest purity are totally colorless, and appear a bright white. The degree to which diamonds exhibit body color is one of the four value factors by which diamonds are assessed. Diamonds have a color grading system that refers to the absence of color. This system goes from D to Z. The more colorless a diamond is, the rarer and more valuable it is because it appears white and brighter to the eye.