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Deep Diamonds

December 20, 2016

The world’s biggest diamonds are helping scientists uncover the secrets of earth’s deep mantle.


A metallic inclusion in a diamond. Evan Smith © GIA

A metallic inclusion in a diamond. (Evan Smith/©GIA)


Deep secrets of large diamonds. I’m Bob Hirshon and this is Science Update.

Supersized diamonds, like the “Constellation” and “Koh-i-Noor”, form deep in earth’s mantle. Gemological Institute of America research fellow Evan Smith says they carry information about where and when they formed.

SMITH (Gemological Institute of America):

I think it’s really astonishing that diamonds, the most valuable and prized of all gems, are coincidentally some of the most scientifically valuable samples of the earth.


In the journal Science, Smith and his colleagues report examining bits that diamond cutters had removed from large gems. They discovered tiny nickel and iron inclusions trapped inside. That means those same metals must pepper the molten rock of earth’s deep mantle. Their presence helps scientists understand how minerals form and cycle between earth’s deep layers and the surface. I’m Bob Hirshon, for AAAS, the science society.

Story by Bob Hirshon