Diamonds are considered the world’s oldest treasure, having formed over 3.3 billion years ago, 200km below the Earths surface. Under conditions of intense heat (900 to 1,300 degrees Celsius) and pressure (between 45 and 60 kilobars), carbon atoms crystallize, forming diamonds. It takes millions of years for a diamond to form, and geologists believe the most recently formed diamonds may be up to 45 million years old. Variations of temperature and pressure can significantly impact the formation of diamonds, and if the conditions are not ideal, it could result in the dissolution of diamonds.
Molten kimberlite (also known as magma) are also formed within the Earths upper mantle under conditions of intense heat and pressure causing it to expand at a rapid rate. This expansion causes the magma to erupt, forcing it into the Earth’s surface and taking along with it the diamond-bearing rocks. These types of “eruptions” have not occurred in recent times, and it is believed that they happened during a time when the Earth was naturally hotter, thus making such eruptions more likely.
Traveling at an incredible speed, the erupted magma forms a pipe to the surface of the Earth. As the magma cools, it hardens to form a rock called Kimberlite, the most significant source of diamonds. The Kimberlite settles in vertical structures known as Kimberlite pipes.