Chocolate Diamonds and a Journey to the Center of the Earth

How one inclusion unlocked the mystery of underground oceans

It’s a question that has fascinated humans for as long as we can remember: “What is beneath our feet?” One theory that may seem unlikely to you and me is that there is a vast layer of water between the Earth’s upper and lower mantle. Now, thanks to skilled scientists, a bit of luck, and a chocolate (brown) diamond, that theory has been confirmed.

The chocolate diamond with the ringwoodite inclusion
The chocolate diamond that unlocked the mystery. Photo credit: Richard Siemens/University of Alberta

The breakthrough came from a tiny inclusion in a diamond that most people would consider worthless (learn more about colored diamonds and their values here). Inclusions, as you may know, are small bits of foreign (non-diamond) material that were trapped inside the diamond during its formation. In general, with engagement rings and other jewelry, the fewer inclusions a diamond has, the more valuable it is (read more about diamond grading here). However, in this case, one inclusion provided the key to unlocking a very old mystery.

Graham Pearson hold the diamond containing ringwoodite
Graham Pearson holding the diamond found to contain Ringwoodite. Photo credit: Richard Siemens/University of Alberta

Ringwoodite, is a substance that has been theorized to exist in this subterranean ocean, but has never been found on Earth except when brought here by meteorites. It only forms in high pressure environments like the Earth’s mantle. Scientists believe that this diamond was formed deep in the Earth’s mantle where a tiny piece of Ringwoodite was encased inside it. Then, a volcanic eruption caused it to be brought to the Earth’s surface where miners in Brazil later discovered it.

Through careful sample handling and high tech analysis, Dr. Graham Pearson and his team were able to verify that the inclusion in this diamond was indeed Ringwoodite. The existence of naturally occurring Ringwoodite confirms the theory that there is a vast amount of water beneath the Earth’s surface. How much water? Scientists believe it may be close to the amount of water in all of the Earth’s oceans combined.

This is a very exciting discovery, and as jewelers we love to hear stories where diamonds are the heros (or at least play supporting roles). You can’t help but be impressed by this little brown diamond and all that it went through to carry this amazing substance to us. So, the next time you look down at that sparkling diamond on your finger, take a moment to imagine the incredible journey it has taken to reach you. What better symbol of love–enduring for a lifetime, forged under pressure, holding priceless treasures inside it–could there be?

A big thanks to Dr. Graham Pearson and Richard Siemens for graciously allowing us to use these great images. Also, checkout the original article on this discovery in the Nature publication.

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