Smith – a analysis scientist at GIA – was inspecting the diamond for inclusions, chemical hitchhikers from the inside of our planet that may reveal how the crystal shaped, and beneath what circumstances. However working with high-value diamonds is a difficult enterprise – ordinarily, it is unimaginable for researchers to get their arms on the most important specimens. They’re generally flown all over the world to go to potential prospects – alas, by no means scientists.

Maya Kopylova, a professor of mineral exploration on the College of British Columbia, says getting samples of any diamonds is difficult, and a lot of the diamonds she works with would have in any other case been thrown away. “Researchers must have a superb relationship with firms and they’re going to by no means offer you helpful samples,” she says. “So, they’ll by no means give us diamonds which are 6mm (0.2 inches) in dimension or bigger.”

Even then, buying them is convoluted and costly – first, Kopylova has to go to the high-security amenities the place diamonds are sorted and determine the specimens she’d like to review. As soon as the acquisition has been accredited, then comes the paperwork – all diamonds should journey with a Kimberley Course of certificates, which proves its provenance and helps to stop battle or “blood” diamonds from getting into the market.

Nevertheless, Smith’s scenario is completely different. At GIA, he has entry to one of many largest collections of diamonds on the planet – hundreds of thousands of gems which have been despatched there to be valued, in order that they are often insured or bought. “If you wish to see one thing uncommon and weird, that is the proper place to go as a result of there are diamonds coming via right here on a regular basis,” says Smith. “Each few days, you would possibly get to borrow a diamond for possibly a number of hours, possibly a day or two and examine it.”

Just a few years earlier, that is precisely what Smith had carried out. Along with a global workforce of scientists, he casually requisitioned 53 of the largest, clearest and costliest obtainable – together with some from the identical mine because the Cullinan diamond – and took them again to his laboratory to view beneath a microscope.

What Smith discovered was revolutionary. Almost three-quarters of the Clippir diamonds contained tiny pockets, or “inclusions” of metallic that had prevented rusting – not one thing you’d discover in bizarre ones – whereas the remaining 15 contained a sort of garnet which solely kinds inside the Earth’s mantle, the layer above its molten core.

Collectively, these inclusions present chemical clues that the diamonds might solely have shaped no fewer than 360km (224 miles) and not more than 750km (466 miles) underfoot. On this Goldilocks zone, it is deep sufficient to clarify the metallic inclusions that hadn’t been uncovered to oxygen, which is considerable increased up, and it is not so deep that the garnet rocks would have damaged down beneath the immense pressures of the decrease mantle. Atypical diamonds, in the meantime, originate beneath the crust, simply 150-200km (93-124 miles) down.  

For his 2020 examine – along with Wuyi Wang, who’s vp of analysis & growth at GIA – Smith analysed the 124-carat diamond and located that it shaped on the deeper finish of the attainable vary – no less than 660km (410 miles) beneath the Earth’s floor.