How Diamonds Are Formed

Diamonds form in the deep layers of the Earth's crust, generally at depths of 150 to 200 kilometres below the surface. These layers are made up of carbon-rich rocks. Under conditions of extreme pressure and high temperature, carbon atoms slowly crystallise to form diamonds — a process that can take millions of years.

Diamonds formed at depth are then carried towards the surface by volcanic eruptions, which expel rocks and minerals from the deep layers of the Earth's crust. Diamonds travel with these rocks and minerals and can be found in volcanic deposits known as kimberlites and lamproites.

Diamonds may also form under similar conditions on planets and other celestial bodies comparable to Earth, such as exoplanets. Scientists believe these extraterrestrial diamonds could help us learn more about the composition and internal structure of such bodies.

In short, diamonds form in the deep layers of the Earth's crust under conditions of high pressure and high temperature over millions of years, before being brought to the surface by volcanic eruptions or movements of the Earth's crust. Some diamonds also form under similar conditions on other Earth-like celestial bodies.