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
As the diamond trade developed, early diamond grades were introduced by various parties in the diamond trade. Without any co-operative development these early grading systems lacked standard nomenclature, and consistency. Some early grading scales were; "I", "II", "III"; "A", "AA", "AAA"; "A", "B", "C". Numerous terms developed to describe diamonds of particular colors: "golconda", "river", "jagers", "cape", "blue white", "fine white", "gem blue", "brown", etc.