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.
Extraterrestrial diamonds
Although diamonds on Earth are rare, extraterrestrial diamonds (diamonds formed outside of Earth) are very common. Diamonds not much larger than molecules are abundant in meteorites and some of them formed in stars before the Solar System existed. High pressure experiments suggest large amounts of diamonds are formed from methane on the ice giant planets Uranus and Neptune, while some planets in other solar systems may be almost pure diamond. Diamonds are also found in stars and may have been the first mineral ever to have formed.