Stuff Matters: Exploring the Marvelous Materials That Shape Our Man-Made World

by Mark Miodownik

The biggest diamond yet discovered is located in the Milky Way in the constellation of Serpens Cauda, where it is orbiting a pulsar star called PSR J1719–1438. It is an entire planet five times the size of Earth. Diamonds on Earth are minuscule by comparison. The biggest yet found is the size of a football. Extracted from the Cullinan mine in South Africa, it was eventually presented to King Edward VII in 1907 on his birthday and is now part of the crown jewels of the British monarchy. This diamond was formed far below the surface of the Earth at a depth of approximately three hundred kilometers, where, over the course of billions of years, the high temperatures and pressures converted a largish-sized carbon rock into the huge diamond. The diamond was then most likely carried to the surface of our planet during a volcanic eruption, where it lay inert and undisturbed for millions of years until it was discovered a mile underground.