Pink diamonds are some of the rarest gems on Earth. Their origins are still a mystery, as most pink diamonds are small and often kept by private collectors. Once cut, their secrets about the Earth’s ancient layers often fade away.
But a newly discovered rough diamond from Botswana is different. This diamond stands out not just for its size or color but for its dual geological history captured within a single crystal. One half of this stone is pink, while the other is completely colorless.
Weighing 37.41 carats, this unique diamond was recovered from the Karowe mine. Scientists at the Gemological Institute of America (GIA) analyzed it, finding it to be a Type IIa diamond. Type IIa diamonds are extremely rare, with very low nitrogen levels and great purity. This clarity makes the color contrast between the two halves striking.
Experts believe this diamond underwent a two-stage growth process. The pink half likely formed first and was later altered by intense geological stress. Then the colorless section formed without any deformation.
The pink hue does not come from trace elements, unlike blue or yellow diamonds. Instead, it results from a process called plastic deformation, where the crystal structure bends under extreme pressure. If the pressure is too intense, the diamond turns brown; too little pressure and it remains colorless.
This Botswana diamond is an incredible opportunity to compare growth conditions within the same crystal. Unlike some diamonds that display color in thin layers, this one has a clean, sharp division between its halves.
The diamond formed over 160 kilometers deep in the upper mantle, where heat and pressure allow carbon to crystallize. It made its journey to the surface through kimberlite, a volcanic rock known for transporting diamonds without damaging them. This journey is crucial; if diamonds ascend too slowly, they can transform into graphite.
The Karowe mine is celebrated for its significant finds. Remarkably, it produced the 2,488-carat Motswedi diamond in 2024, one of the largest ever found. Modern techniques at Karowe ensure that large crystals are not harmed during extraction, allowing valuable insights into their internal makeup.
Researchers are increasingly associating the formation of pink diamonds with tectonic events rather than just surface conditions. A recent study in Nature Communications examined the Argyle diamond deposit in Australia, which has produced over 90% of the world’s known pink diamonds before it closed in 2020. This study discovered that Argyle’s volcanic rock formed during the breakup of the supercontinent Nuna, creating rift zones in the Earth’s crust.
By using uranium-lead dating methods on various minerals, researchers found that this tectonic activity created the conditions necessary for pink diamonds to form. The new Botswana diamond shows a similar growth pattern, suggesting that tectonic forces play a key role in the development of these rare gems.
As researchers analyze the Botswana diamond, they employ non-destructive techniques to map its internal structures and color zones. This includes detailed imaging and analysis to identify specific defects that give the pink hue. Comparing both halves will provide insights into how different physical conditions impact diamond formation.
Experts are evaluating whether the boundary between the pink and colorless parts can be preserved during cutting. While the pink section may be more valuable on the market, the diamond as a whole offers a wealth of information for scientific research.
In conclusion, this pink and colorless diamond is not just a rare find; it holds the promise of unlocking new secrets about the Earth’s interior processes. Its dual characteristics may shed light on the geology beneath our feet and provide clues about how such treasures are formed.
For more insights on diamonds and their formation, check out the GIA for further exploration of this fascinating topic.
