The Formation of Diamonds Under Our Feet

The Secret Ingredient: Pure Carbon

The diamond, the most famous precious stone, is actually a pure and crystallized form of carbon. Contrary to what one might think, it is not the result of a miraculous process, but the result of a long and violent geological process. The formation of diamonds requires conditions so extreme that they can only exist deep inside our planet. Diamonds are therefore much more than just minerals; they are silent witnesses to the Earth's tumultuous history, locked within a perfect crystalline structure.

The Extreme Conditions of Their Birth

The transformation of carbon into diamond is a feat of nature that can only occur under a unique combination of pressure and temperature.

Enormous Pressure and Temperature

The majority of natural diamonds form in the Earth's layer called the mantle, at depths ranging from 150 to 200 kilometers. At this location, temperatures reach between 900 and 1300 °C, and the pressure is about 45 to 60,000 times greater than that on the surface. These conditions are so intense that they force carbon atoms to bond together very tightly, creating the ultra-resistant crystalline structure that characterizes a diamond.

A Journey to the Surface

Diamonds do not make their way to the surface on their own. They are transported during very specific and violent volcanic eruptions that occur at these depths. These eruptions create conduits called kimberlite pipes or lamproite, which are volcanic rocks in which the diamonds are trapped. The molten rock and diamonds ascend to the surface at incredibly high speeds, preventing the diamonds from turning into graphite (their less stable form) under the drop in pressure.

Extraction and Discovery

Once the kimberlite pipes cool, they form deposits that can be mined. It is in these deposits that most diamonds are found. They can also be discovered in riverbeds or oceans (alluvial deposits), as the erosion of the kimberlite rocks has freed them over millions of years.

Age and Rarity

Most diamonds are incredibly ancient, forming billions of years ago, long before the dinosaurs. Their rarity and unique formation process are what make them so valuable. Today, science allows us to create synthetic diamonds in a laboratory, replicating the extreme conditions of the Earth, but the natural process and geological history behind each stone remain a marvel of nature.