Rare half-pink, half-colorless 37-carat diamond discovered in Botswana

The rough diamond, examined by experts at a Gemological Institute of America (GIA) laboratory in Botswana, measures about 24.3 by 16 by 14.5 millimeters. Researchers say the gem likely formed in two separate geological stages deep beneath the Earth's surface.

The pink half appears to have originally been colorless before undergoing intense pressure changes.

"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," said Sally Eaton-Magaña, senior manager of diamond identification at GIA, Indian Defence Review reported.

Pink diamonds are exceptionally rare. Unlike diamonds that take on color due to impurities like trace elements or radiation exposure, pink diamonds get their hue from structural distortion: their atomic lattice gets squeezed or twisted under extreme geological forces. Too much deformation turns diamonds brown, which is why pink stones form only in very specific, delicate conditions.

"It's kind of like Goldilocks," Luc Doucet, a senior research geologist at Curtin University in Australia, told Live Science. "There are a lot of brown diamonds, and very, very few pink diamonds."

For this diamond to display two distinct color zones, scientists say its pink half must have formed first and been altered by geological pressure, with the colorless half growing later in more stable conditions.

Similar two-color diamonds have been found before, but they are typically far smaller, often just 2 carats or less. At more than 37 carats, this Botswana specimen stands out as an extraordinary find.

The gem was recovered from the Karowe mine, a site known for producing some of the world's most notable diamonds. Previous discoveries there include the 2,488-carat "Motswedi" diamond and the 62-carat "Boitumelo" pink diamond.