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 usually form in the thick, rigid mantle roots beneath old continents, at depths of up to about 200km. The mantle is the thick layer of hot rock between Earth’s core and outer “shell” known as the crust.
Although their size and value attract attention, our interest in CLIPPIR diamonds lies in the journey they record. Because they originate at depths far beyond our reach, diamonds are valuable for understanding parts of Earth’s interior that we cannot directly observe. CLIPPIRs are especially rare messengers from the deep mantle. Studying them is one of the few ways we can learn how rocks and carbon are recycled in the Earth’s deep interior, and how our planet reshapes itself over hundreds of millions of years.
