Most diamonds formed between one and three billion years ago. For context: the oldest dinosaur fossils are about 230 million years old. A typical diamond predates them by a factor of ten.
They form approximately 150 kilometres below the earth's surface, where pressure reaches 45,000 to 60,000 atmospheres and temperatures exceed 1,000 degrees Celsius. Under these conditions, carbon atoms bond in a specific tetrahedral structure - each carbon atom connecting to four others - creating the exceptionally strong lattice that makes diamond what it is.
The remarkable part is how they get to the surface. Diamonds don't erupt through ordinary volcanic activity. They travel in a type of magma called kimberlite, which rises from deep in the earth's mantle at extraordinary speeds - researchers estimate kimberlite eruptions travel at 20-70 kilometres per hour, reaching the surface in hours or days.
This speed matters. Diamond is only stable at the pressures of the deep earth. A slow ascent would allow it to convert back to graphite - the stable form of carbon at surface conditions. The violent speed of kimberlite eruptions essentially freezes the diamond structure in place before it can revert.
So a mined diamond in a ring made this century spent three billion years underground before a geological accident brought it to the surface. It was extracted, cut, polished, and set - passing through perhaps a dozen hands on the way.
The lab-grown diamonds we use at Carat Theory take a different path: the same carbon crystal structure, grown in weeks rather than aeons. The science is entirely different. The resulting stone is, by every physical measure, the same.
