The largest diamonds in the British Crown Jewels may be pieces of the ancient ocean floor, which have drifted down into the interior of our planet – then come back up again.
It was April 1905, and three months earlier, the surface manager at the Premier Mine in South Africa had been completing a routine inspection 18ft (5.4m) underground, when he glimpsed a reflected light in the rough wall above him. He assumed it was a large piece of glass hammered in by colleagues as a practical joke. Just in case, out came his pocket knife, and after some digging… the knife promptly snapped. Eventually the rock was removed successfully, and revealed to be a bona fide diamond – a monster 3,106.75-carat stone, almost the size of a fist. It was not only enormous, but unusually transparent.
The Cullinan, as it became known, is the largest diamond ever found. Once it had been polished and cleaved into several more manageable stones, the largest crystal it yielded would shine like the cool glow of a star in a distant galaxy. As a result, this stone – the Cullinan I – is sometimes known as the Great Star of Africa.
Nearly 120 years later, the mega-diamond has not been forgotten. During the late Queen Elizabeth II’s funeral procession, several of the Cullinan’s descendants were placed on the Monarch’s coffin, and rode along with her – they were only removed as she was lowered into the royal vault. That’s because today these giant gems are part of the Crown Jewels, normally kept in the Tower of London and brought out for state events – the Cullinan I now resides in the British Sovereign’s Sceptre, while its next-largest sibling, the Cullinan II, is embedded in the Imperial State Crown.
However, before the rough diamond could have its makeover and take its place in history, it needed to be sold – and London was chosen as the most promising location to do this. This presented a problem: how do you transport such a valuable stone 7,926 miles (12,755km), without it being stolen?
In the end, the precious rock was sent all the way from Johannesburg by ordinary registered post, at a cost of just three shillings or about 75 US Cents at the time (around £11.79 or US$13.79 today). Meanwhile, a replica of the diamond made the long voyage to London by steamboat – it was placed conspicuously within the captain’s safe and guarded by police detectives as a decoy. Amazingly, both made it to their destination. After years of failing to sell, the diamond – the real version, this time – was purchased by the Transvaal government for £150,000 (£20m or US$22.5m today) and gifted to King Edward VII.
But though they’re renowned across the globe for their size and transparency, these characteristics are no accident. The Cullinan was a “Clippir” diamond – a member of a special category of the very largest and clearest examples ever found. And there is more to them than meets the eye.
For all their beauty, diamonds are really fragments of the deep Earth – intriguing geological anomalies disguised as mere jewelery. These strange rocks are capsules from another world – a mysterious realm of unfathomable pressures, swirling green rock, and elusive minerals, far below the Earth’s surface. Scientists around the globe have been studying them for decades to reveal the region’s secrets – and intriguingly, it’s the very diamonds that we value most that have the most unusual stories to tell. In fact, large rocks like the Cullinan are transforming our understanding of the inside of our planet.
