Smith — a senior analysis scientist at GIA — was testing the diamond for inclusions, chemical hitchhikers from our planet’s inside that reveal how and beneath what situations the crystal fashioned. However working with high-value diamonds is a tough enterprise – usually, it is inconceivable for researchers to get their fingers on giant samples. They’re generally flown all over the world to satisfy potential prospects – alas, by no means scientists.
Maya Kopilova, a professor of mineral exploration on the College of British Columbia, says it is troublesome to get samples of any diamonds, and a lot of the diamonds she works with would in any other case be thrown away. “Researchers need to have good relationships with corporations, they usually by no means offer you treasured samples,” he says. “So, they by no means give us diamonds 6mm (0.2 inches) in measurement or bigger.”
Even then, buying them is convoluted and costly — first, Kopilova should go to high-security services the place diamonds are sorted and determine the samples he desires to review. As soon as the acquisition is accepted, the paperwork comes – all diamonds should journey with a Kimberley Course of Certificates, which proves its origin and helps forestall battle or “blood” diamonds from getting into the market.
Nonetheless, Smith’s scenario is completely different. At GIA, they’ve entry to one of many largest collections of diamonds on the planet – hundreds of thousands of gems despatched there to be valued in order that they are often insured or offered. “If you wish to see one thing uncommon and weird, that is the place to go as a result of diamonds come up right here on a regular basis,” Smith says. “Each few days, you may borrow a diamond for a couple of hours, possibly a day or two, and examine it.”
A couple of years in the past, Smith did precisely this. With a world group of scientists, he casually requested 53 of the most important, clearest and costliest obtainable – some from the identical mine because the Cullinan diamond – and took them again to his laboratory to view beneath the microscope.
What Smith discovered was revolutionary. About three-quarters of the Clipper diamonds had small pockets or steel “inclusions” that averted corrosion — not the type you’d discover in abnormal ones — whereas the remaining 15 contained a kind of garnet that solely kinds inside the Earth’s mantle. A layer above its molten core.
Collectively, these inclusions present chemical clues that the diamonds could have been fashioned a minimum of 360km (224 miles) and 750km (466 miles) underfoot. On this Goldilocks zone, which is deep sufficient to clarify steel inclusions not uncovered to oxygen, it’s at excessive altitude and never so deep that the garnet rocks fracture beneath the immense strain of the decrease mantle. Regular diamonds, in the meantime, originate simply 150-200km (93-124 miles) beneath the crust.
For his 2020 examine — with Wui Wang, vp of analysis and improvement at GIA — Smith analyzed the 124-carat diamond and located it fashioned on the deepest finish of the doable vary — no less than 660km (410 miles) down. Earth’s floor.