How Are Diamonds Created?
Diamond-Producing Conditions
Certain conditions must exist in nature for diamonds to be created. Specifically, carbon-bearing materials must be exposed to extremely high temperatures, between 1652-2372 degrees F, and very high pressures, between 45-60 kilobars. These kinds of conditions exist only at depths of 90-120 miles beneath the earth’s surface and sometimes deeper than depths of 300 km. Such conditions are found in the stable and thick portions of continental plates in parts of the lithosphere called cratons.
Time & Origin
How large a diamond is will depend on the total time it had to grow. In other words, the more time, the bigger the diamond will be. Diamonds take an exceptionally long time to form, and most diamonds found on the earth’s surface are over a billion years old. You can also find diamonds in the impact craters of meteors. The tiny diamonds found in the wake of a meteoric strike are called microdiamonds or nanodiamonds. These diamonds are rarely used in the industry because they serve mostly as indicators of ancient meteor impact sites. A diamond is composed of pure carbon from both inorganic and organic sources. Diamonds that originate from inorganic sources are called harzburgitic diamonds, while those from organic sources are called eclogitic diamonds.
Volcanic Eruptions
Volcanic eruptions also help bring diamonds to the surface. Such eruptions bring rocks that carry diamonds close to the earth’s surface. To do so, the eruptions must have magma originating on a very deep level, usually more than 90 miles below the surface. This is about three times the average magma depth for a volcano, so this does not happen frequently. When an eruption takes place, volcanic pipes circulate diamonds to the surface. However, not all volcanic pipes contain diamonds, and even if they do, the diamonds might not be economically profitable. Keep in mind that magma does not actually contain diamonds; it simply carries them to the surface. After they are transported to the surface, diamonds sometimes erode or are distributed over a large area.
