Back in January, researchers at Sun Yat-sen University in Zhuhai, China, theorized that Mercury, the tiniest planet in the solar system and the one that orbits closest to the Sun, could be littered with an untold wealth of diamonds.

They argued that the pockmarked surface of Mercury is evidence of the planet being pummeled by asteroids over billions of years. Since Mercury's surface is covered in carbon-rich graphite, the impact pressure from those events would have produced enough energy to transform the surface carbon into “shock diamonds.”

Now, a new study published by researchers at China’s Center for High Pressure Science and Technology Advanced Research in Shanghai floats the idea that there's a thick layer of diamonds hidden hundreds of kilometers below Mercury's surface.

Yes, Mercury may be flush with diamonds — inside and out.

NASA’s Messenger was the first spacecraft to orbit the planet back in 2011. It took nearly seven years for the probe to complete its 224-million-mile trip, and one of the important takeaways from the mission was that Mercury’s dark grey surface contained a lot of graphite.

The Shanghai researchers recognized that where there's a lot of graphite, there's a lot of carbon. And where there's a lot of carbon, there could be — under the right pressure and heat — a lot of diamonds.

It was previously believed that Mercury's relatively weak gravitational field and modest pressure within its ancient magma ocean would have been insufficient to generate diamonds.

But, according to iflscience.com, the Chinese researchers generated new models of Mercury’s gravity field that called this into question.

The new data encouraged the team led by Yongjiang Xu to expose samples of the elements that were likely present during Mercury's formation to 7 gigapascals of pressure at almost 2,000°C (3,600°F).

They concluded that there were at least two scenarios where diamonds could have been formed on Mercury.

The first theory is that diamonds formed within a magma ocean, but this would have been possible only if great quantities of sulfur were present at the time.

The second, more likely, theory is that diamonds were squeezed out of the core as the magma ocean crystallized.

The study was recently published in the journal Nature Communications.

If diamonds do exist in massive quantities on Mercury, it's unlikely that the economics of mining them would ever make for a viable business plan. What's more, its inhospitable daytime temperatures can reach 800°F, higher than the temperature inside a commercial pizza oven.

The BepiColombo mission launched in October 2018 will descend into Mercury's orbit in 2025. A joint effort of the European and Japanese space agencies, BepiColombo is equipped with high-resolution cameras that could provide conclusive evidence of diamonds on that planet’s surface.

Credit: Image courtesy of NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution Of Washington.