Beyond the Hype of Lab-Grown Diamonds - gizmodo

Billions of years ago when the world was still young, treasure began forming deep underground. As the edges of Earth’s tectonic plates plunged down into the upper mantle, bits of carbon, some likely hailing from long-dead life forms were melted and compressed into rigid lattices. Over millions of years, those lattices grew into the most durable, dazzling gems the planet had ever cooked up. And every so often, for reasons scientists still don’t fully understand, an eruption would send a stash of these stones rocketing to the surface inside a bubbly magma known as kimberlite.