Plenty has been said about how much of outer space, and even the oceans, have been left undiscovered, but what you may not hear about as much is the abundance of undiscovered wonder under the Earth’s surface. Sure, it may not be full of life, but there’s still a great deal to be studied!

The fact of the matter is that most of the fascinating things hiding under our soil can’t be easily studied because exploring the Earth’s center is usually just the work of science fiction. One massive mine in South Africa changed all that! What was discovered in its depths rivals the beauty of any natural wonder above the planet’s surface… and its value, too.

The Cullinan Diamond, found in South Africa’s Premier Mine, is the largest rough diamond of gem quality in the world. A diamond like that might not be ready to be part of jewelry like an engagement ring, but with some polishing it could be!

This discovery was huge news when it was discovered in South Africa in 1905. The British royal family was so enchanted by the Cullinan Diamond that a portion of it was used in the royal crown jewels, and Queen Elizabeth II kept other parts of the stone for her private collection!

Even to this day, of all the known diamonds in the world worth 400 carats or more, as many as 25 percent of them have been found in the Premier Mine. That’s absolutely huge for just one mine out of the many across the globe.

Unsurprisingly, considering its sheer size, the Cullinan Heritage Diamond is also the most expensive rough diamond ever sold, for a whopping $35.3 million in a 2010 auction. Additionally, it’s the world’s largest source of rare blue diamonds.

Just about every rock enthusiast worth their salt knows how valuable diamonds are, but following that initial discovery of the Cullinan Diamond, something else, within the precious stones themselves, made people take notice…

It all started with the chemical compound calcium silicate perovskite, which is usually found over 400 miles below the Earth’s crust. Although it’s actually the fourth most common mineral in the world, throughout most of human history, scientists couldn’t get a good look at it.

At the same time, it’s important to note that the enormous size or staggering monetary value of the massive Cullinan Diamond is hardly the only remarkable thing about it.

You see, diamonds are usually formed naturally anywhere between 90 to 120 miles under the surface of the Earth, but this special diamond started forming around 430 miles under the Earth’s surface, which made a huge difference by the time it was finally discovered in 1905!

The Cullinan Diamond was surrounded by calcium silicate perovskite, and because it was in an environment with pressure roughly 250,000 times that of sea level, by the time it reached the Premier Mine, some of the compounds got trapped inside the diamond, making it more accessible than ever!

Graham Pearson, a geochemistry professor at the University of Alberta, studied the phenomenon closely and knew how groundbreaking it was. “Nobody has ever managed to keep this mineral stable at the Earth’s surface,” he explained in an interview.

Furthermore, the way in which the chemical compound finally became obtainable was unprecedented. “The only possible way of preserving [it] at the Earth’s surface is when it’s trapped in an unyielding container like a diamond,” Graham continued.

Even though it took so long for the compound to be obtained, that doesn’t mean it’s scarce. In fact, Pearson explained that there could be “as much as Zetta tons of this perovskite in deep Earth.” A Zetta ton is a one followed by 21 zeros, so there’s no shortage of perovskite!

Granted, even though they hadn’t gotten their hands on it for so long, scientists long knew there was plenty of perovskite since the 1960s. In fact, even going as far back as the 1970s, scientists had been attempting to synthesize the substance.

Still, nothing compares to studying the real deal, which long seemed impossible. The synthetic material from diamond anvil cells heated with lasers was the best they had to work with, and finally getting their hands on real perovskite opened up exciting new possibilities for research.

For example, with real perovskite scientists can now study the naturally-occurring perovskite to learn more about how carbon cycles deep within the Earth function, as well as investigating the Earth’s crust under the ocean’s surface.

Moreover, perovskite originated in the Earth’s crust. “When that [perovskite] gets subducted down in the Earth’s mantle,” Pearson continued. “It keeps going until it transforms into higher and higher pressure mineral phases.”

Pearson had experience studying a rare material that scientists had previously only dreamed of obtaining because in 2014 he helped lead the discovery of ringwoodite, the Earth’s fifth most plentiful mineral, but another one that exists mostly within the mantle.

As for the Cullinan Diamond, a great deal of work still lies ahead for Graham Pearson and all of the other scientists who have been so eager to study it, and the surprising chemical compound that it carried, for so many years.

Even when it comes to the Cullinan Diamond itself, nobody’s entirely sure how old it even is. Pearson says it may be “quite young [or] a billion years old… we have a program looking at super-deep diamonds with the purpose of obtaining information.”

If nothing else, however, Pearson says this is just one example of how amazing modern science can be. “You build on theoretical predictions—in this case, from seismology—and once in a while you’re able to make a clinching observation that really proves that the theory works.”

Even though most people associate the value of diamonds with the gem itself, the Cullinan Diamond proves that a rock can be so much more than what it appears on the surface. And sometimes, you have to dig deep for the real value.

And one Brazilian miner can certainly attest to that. In the summer of 2017, the 50-year-old father of one—identified only by the initials FG—made a startling discovery. He’d been working in a mine about 656 feet underground when he happened upon something that would change his life forever.

This mine, to be more specific, was the Carnaiba mine in Bahia, Brazil, and it was known for being particularly gem-rich. FG, along with his employer, the Bahia Mineral Cooperative, had the legal authority to mine in the region.

For those reasons, it shouldn’t have come as too much of a surprise when FG made his discovery, tucked away in a wall of mica schist at the end of the mine’s intricate tunnel system. But the find was just that impressive…

Daily Mail

Hidden in the rocks was a gemstone laced with emerald beryls. The entirety of the gemstone weighed 794 pounds, as FG would later find out, and it stood just over four feet tall. The thing was massive—and impressive.

About the emeralds, FG said, “their quality is superb and by far the best I’ve ever seen and I’ve been in the industry for nearly 30 years.” In other words, this stone would make FG rich beyond his wildest dreams! But there were some complications…

Daily Mail

For starters, as mentioned, FG’s find weighed a whopping 794 pounds. To put that into perspective, that’s about the size of two silverback gorillas or a little smaller than a fully grown racehorse. In other words…

Joe Hogarty / flickr

FG wasn’t able to lug that stone 656 feet back to the surface on his own. He was going to need help, but to invite help would be costly—literally. He could no longer consider himself the sole owner of the yet-to-be-priced gemstone.

WION / YouTube

That was a sacrifice FG felt he could make, however. He explained the retrieval process this way: “Extracting the stone was extremely difficult. It took 10 of us more than a week to get it out because it was 200 meters down in the ground.”

The stone “was cut out of the area, where it was embedded, in one piece and all hands were needed to lift it to the mine shaft where it was raised to the surface by a winch.” So, did that mean there are now 11 people claiming ownership of this stone?

Instead of trying to work with 10 others to determine the gemstone’s fate, FG paid each helper, making himself the sole owner of the emeralds. But now for the (possibly) million-dollar question: how much was this thing actually worth?

FG couldn’t surmise an exact value for the emeralds. “Personally, I don’t know what the value of this piece is,” he said, “because it will be led by market demands.” But the experts ventured a few guesses…

While finding a gemstone that large is already rare, FG’s find was particularly rare because of “considerable size and the quality of its gigantic crystals.” So, how did that affect the price of this 800-pound stone?

Daily Mail

Estimates suggested the stone would fetch a payday close to $319 million! To put that number into perspective, that’s the net worth of country singer Toby Kieth or famed basketball star Kobe Bryant. But would anyone pay that?

According to FG, he’d already fielded calls “from interested parties including potential buyers from Europe, Arab Emirates, America, India, and China, who are keen to open negotiations.” The future payday, though, had serious consequences…

When your $319 million gemstone makes national news, it can put a bit of a target on your back. FG knew it—and it terrified him. He had to come up with a plan to protect the gemstone—and more importantly—his family.

Public Radio International

With visions of gun-wielding Brazilian gangs blowing a hole in a wall to get his gemstone—as they’d done in another heist, seen here—FG kept his treasure under the watchful eye of armed guards for 24 hours a day, seven days a week. He didn’t stop there, either.

FG took extreme measures to protect the stone’s location. “I can’t reveal anything about the whereabouts of the stone,” FG said, or “how it’s being kept and how much I paid for it.” FG even had the stone moved regularly between different secure locations. He took one more precaution, too…

FG’s use of a pseudonym was intentionally done in order to hide his real name. He also only spoke to the media through his lawyer (pictured). He didn’t want anyone tracking down him or his family to obtain the gemstone’s location. It was a wise move!

AOL

But despite the target on his back, FG didn’t rush in his decision-making. “For now,” he said, “I’m keeping the rock heavily guarded and out of sight until I reach a decision on whether to sell it or display it in museums here in Brazil.”

AOL

Whatever his decision, the stone would likely end up not as jewelry, but on display, because of the high quality of the gemstones. While we’re so accustomed to seeing rocks everywhere, we can often forget that they’re more special than they initially let on.