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On this day in 1905, the world’s largest diamond was unearthed at the Premier Mine in South Africa. Then it was promptly yeeted out a window.

When the stone was brought to the mine’s office, the clerk on duty dismissed it as a worthless hunk of crystal. Diamonds simply weren’t that big. So he tossed it—literally.

Cooler heads prevailed, and the clerk was convinced to see the gem for what it was: exceptional. It weighed 3,106 carats (more than a pound) and measured 4 inches long, with remarkable color (or lack of it) and clarity.

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The diamond was found 18 feet underground and would be named for the mine’s owner, Thomas Cullinan. Based on its size and shape, geologists estimate that it formed more than a billion years ago, as deep as 400 miles below Earth’s surface.

The Cullinan diamond was briefly exhibited in Johannesburg before being shipped to London. Much ado surrounded its steamboat journey—locked in the captain’s safe and protected by guards. But the reality is that the stone was simply mailed to England in an unremarkable box; the steamboat was a decoy.

Once it went up for sale, a problem emerged. With a stone that size, the idea of cutting it was intimidating. It sat unsold.

In 1907 the South African province of Transvaal—then under British rule—purchased it for 150,000 pounds for King Edward VII as a 66th birthday gift, a gesture of loyalty that today carries complicated implications of colonization.

The king sent the stone to Amsterdam to be cut and polished, a herculean task that took three people eight months. The first step was to split the diamond. But the first blow broke the saw, and it took four days just to cut a groove.

Fun Fact

Queen Elizabeth II inherited the diamonds from Queen Mary and called them “Granny’s Chips.”

Eventually, the Cullinan yielded 9 major stones and 96 minor ones. The two largest, Cullinan I (530 carats) and Cullinan II (317 carats), were added to the British crown jewels: one on the Sovereign’s Sceptre with Cross, the other in the Imperial State Crown. They remain the two largest, colorless diamonds in the world. Several other major stones went to the king’s daughter-in-law Queen Mary.

And if the Cullinan wasn’t impressive enough already, the original stone showed signs of cleavage—evidence that it may once have been part of an even larger diamond.

Imagine trying to heave that out the window.

By the Numbers
  • 300+: Diamonds of more than 100 carats found at the Premier Mine
  • 1 million+: Carats mined annually from the Premier Mine
  • 2,503 feet: Current mining depth at the Premier Mine
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