Where do world’s biggest diamonds come from? Geologists now have answers

Some of the most extraordinary gems ever found belong to a rare class of diamonds known as CLIPPIRs (Cullinan-like, Large, Inclusion-Poor, Pure, Irregular, Resorbed). They make up less than 1% of all diamonds on Earth, and include three of the largest diamonds ever recovered, the Cullinan, at 3,106 carats, found at the Premier mine in South Africa; the 1,111 ct Lesedi La Rona, discovered at the Karowe mine in Botswana in 2015 and sold for US$53 million in 2017; and the 2,492 ct Motswedi recovered from the Karowe mine in 2024.CLIPPIRs are not ordinary diamonds. They are part of a group known as “superdeep” diamonds that form more than 400km beneath our feet in a region of Earth’s deep interior called the mantle transition zone. This is much deeper than ordinary gem-quality diamonds, which u