Live Science has a story about the discovery of a very large pink diamond. The diamond weighs 37.4 carats. It was discovered in Botwana and likely formed in two stages as it has two colors… pink and colorless.

The pink half probably formed first, but from what scientists know about colorful diamonds, there’s a good chance that it wasn’t always this rosy, Sally Eaton-Magaña, senior manager of diamond identification at GIA, said in a statement emailed to Live Science. “The pink section likely was initially colorless and then plastically deformed, perhaps by a mountain-forming event millions of years ago, resulting in its pink color, with the colorless section forming at a later time,” she said.

Pink diamonds are incredibly rare, and it’s still unclear exactly how they form. Diamonds originate more than 100 miles (160 kilometers) beneath Earth’s surface, inside a planetary layer called the mantle. Extremely high temperatures and pressure bind carbon atoms together into a tight lattice, and this structure can rise quickly to the surface through volcanism, giving us rough diamonds.

Diamonds can acquire color through impurities that get locked inside the lattice, but this is very rare because few elements are small enough to penetrate the mineral structure. Another way diamonds can become tinted — usually green — is through radiation, if nearby rocks contain elements such as uranium that can “steal” carbon atoms and create vacancies in the mineral structure.

But pink diamonds are the product of structural deformity, meaning their lattice structure has been bent or compressed through geological processes. Temperature and pressure conditions have to be just right for diamonds to turn pink, because too much deformation turns the gems brown.