…and you thought you were under a lot of stress.
GABORONE, BOTSWANA — The GIA laboratory in Botswana recently examined an extraordinary 37.41-carat pink-and-colorless rough diamond, reportedly from the Karowe mine — the same source that produced the ginormous 2,488-carat (brownish) Motswedi diamond.
What makes this stone so intriguing is its sharply defined color boundary — one section near colorless, the other distinctly pink — hinting that the diamond may have formed in two separate geological stages.
“It is generally understood that pink color in diamonds results from significant stress causing a change in the diamond’s crystal structure known as plastic deformation,” said Dr. Sally Eaton-Magaña, senior manager of diamond identification at GIA in Carlsbad, California. “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.”
As we noted in our last report on the Motswedi, browns also get their color from stress. And it is fairly obvious with both the bicolor pink here, as well as the brown Motswedi, that both encountered a lot before being discovered.
The research, authored by Dr. Eaton-Magaña, along with GIA Gaborone’s Kgotlaetsho Baatshwana (senior analytics technician) and Norma-Jean Osi (analytics technician), is now available on GIA’s website.
The article includes high-resolution photos as well as a video, and will appear in the next issue of Gems & Gemology.
Extraordinary Large Bicolor Natural Rough Diamond
Sally Eaton-Magaña, Kgotlaetsho Baatshwana, and Norma-Jean Osi
October 10, 2025
Tap here to go directly to GIA’s website and the feature story,
Extraordinary Large Bicolor Natural Rough Diamond
