In the last 20 years scientists have discovered new sources of diamond. In Kazakhstan, for example, diamonds formed in buried crust that returned to Earth's surface. Meteor impacts produce immense pressures, and diamonds can be formed and sprayed among the impact debris.
Meteorites also experience impacts themselves and can contain diamonds.
And the most ancient meteorite material contains star dust, the remnants of the death of stars. Some of this star dust is extremely tiny bits of diamond, just big enough to be crystals and older than the solar system itself. Recently scientists have found traces of diamond around meteor impacts. It is now suspected that diamonds form in most major impacts, becoming a new indicator of ancient cosmic collisions. The diagrams above illustrate the formation of a UHP terrane that can yield diamonds.