Not all diamonds are formed deep within the Earth. Some are born in the intense heat and pressure as a meteorite crashes into the Earth's surface, or collides with other bodies in space. Others, too tiny for the eye to see, are scattered across the solar system as stardust, spewed out during the death of ancient stars.
In 1891, scientists tried to saw through a fragment of meteorite from the Cañon Diablo in Arizona, USA. They destroyed both an iron blade and an emery grinding wheel in the process. The reason it was so hard to cut is that the meteorite was full of tiny diamonds, the hardest natural substance on earth.
At first, they thought the diamonds came from outer space. However, they could have formed on Earth in the intense heat and force of the meteorite’s impact. This was so great that it formed a crater 1,200m wide and 175m deep.
Scientists have discovered diamonds millions of times smaller than a grain of sugar, trapped in meteorites older than the Earth.
When heated, these minute diamonds released tiny amounts of a gas called xenon. Xenon occurs in a range of different forms. The mix found in the diamonds has not been found on Earth before, but it is similar to the mix that might exist in gases surrounding distant dying stars, called supernovae.
Were these diamonds once hurled out from a supernova? They could then have become trapped in the swirling mass of gases and dust from which our solar system formed.