Study of rare diamonds unlocks more of Earth's secrets

In two recent scientific papers, GIA researchers and their colleagues at other leading research institutions share their latest discoveries based on information gleaned from extremely rare and pure diamonds from very deep within the earth.
A paper published in scientific journal Science Advances reveals that a hydrous rock called serpentinite, which forms in cracks in the ocean floor, is a critical ingredient in some of the largest and rarest diamonds that form at extreme depths.
The research, co-led by Evan Smith from GIA and Peng Ni from the Carnegie Institution for Science, discovered an isotopic "fingerprint" of iron trapped in type IIa gem diamonds from Letseng, Lesotho. It is well understood that oceanic tectonic plates slide down into the mantle over millions of years, a process called subduction. This study reveals that some sinking ocean plates act like a giant conveyor belt capable of transporting water, carbon and other surface materials down into the interior of our planet— to depths of 360 to 750 km where these "super-deep" diamonds form. Understanding this deep recycling pathway is critical to understanding the evolution of the oceans and atmosphere, GIA notes.

Alex Shishlo for Rough&Polished