A billion-year-old black diamond, considered the largest faceted diamond on Earth, has been put up for auction, according to the BBC.
There are various theories about the origin of the gemstone, called the Enigma, including that it came from space.
Weighing 555.55 carats, the gemstone is considered extremely heavy for a diamond, it weighs about as much as a banana.
Sotheby’s auction in London is expected to pay more than £ 4.4m ($ 6m) for the stone by the end of online bidding next week.
This stone is carbonado, one of the hardest forms of natural diamond.
The age of black diamonds is usually 2.6 to 3.2 billion years – the time before the appearance of dinosaurs.
The age of the Earth itself is about 4.65 billion years, which is not much older than black diamonds.
Aaron Celestian, a geologist at the Los Angeles Museum of Natural History, said the carbonados “could have formed very deep in the bowels of the Earth, much deeper than what we already know about diamonds.”
“There are hypotheses that suggest that they formed at the point of collision when a large asteroid fell to Earth,” he said.
The competing theory is that black diamonds could have formed in outer space like the fall of the Earth. ”
Sotheby’s describes the sale as “an opportunity to buy once in a lifetime one of the rare billions of years of miracles known to mankind.”
The diamond weighs exactly 555.55 carats and has 55 faces. Carbonados is extremely rare and has been found only in Brazil and the Central African Republic.
Because they contain osborite, a mineral found only in meteorites, they are thought to have originated in space.
However, their exact origin is shrouded in mystery.