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.
Diamonds as an investment
Diamonds of smaller sizes are traded in parcels of similar stones, called 'melee', after the French word for mix. Generally diamonds of exactly similar size, cut, shape, color and clarity are used in a single piece of diamond jewelry. If not, the stones would not match and the piece would not sell. Small recycled diamonds are treated differently from large individual stones. A single small diamond has limited value by itself. It is only of use if it can be matched with other similar diamonds, reset into jewelry and sold to a customer, thereby creating value. Small recycled diamonds need to be sorted, recut and resold to manufacturers in large parcels to allow them to pick matching stones to set in jewelry.