37-carat half-pink, half-colourless rarest diamond unearthed in Botswana mines

Geologists at the Botswana mines made a remarkable discovery: a diamond that is split cleanly in two. One half is brilliant pink, while the other half is colourless. The formation is so rare, geologists believe it may have crystallised during two separate geological events more than 100 miles below the surface.

The diamond was discovered by Lucara Diamond Corp in the Karowe mine in Botswana and is now held by the Gemological Institute of America (GIA). The site is renowned for yielding some of the world’s largest and most exceptional diamonds. The country accounts for roughly 20 per cent of the world's production.

“The pink section likely was initially colourless and then plastically deformed, perhaps by a mountain-forming event millions of years ago, resulting in its pink colour, with the colourless section forming at a later time,” said Sally Eaton-Magaña, senior manager of diamond identification at GIA, told Live Science.

How do diamond get their colour?

Pink diamonds are incredibly rare; this 34-carat dual coloured diamond is almost unheard of in nature. "It's kind of like Goldilocks," Luc Doucet, a senior research geologist at Curtin University in Australia, previously told Live Science. “There are a lot of brown diamonds, and very, very few pink diamonds.”

Scientists are still unclear how pink diamonds are formed. Extremely high temperatures and pressure bind carbon atoms together in a tight lattice, and this structure can rise quickly to the surface through volcanism. Diamonds acquire colour through impurities. One way diamonds get tinted is through radiation of nearby elements, for example, Uranium, which is usually green, can 'steal' carbon atoms from the diamond, creating vacancies in the mineral structure. But pink diamonds are extremely rare; it is not certain how they are formed. Scientists predict they are formed via geological processes, where exact pressure and temperature are needed for structural deformity; too much deformation can turn them brown.