I’ve always said peanut butter is a girl’s best friend, and now there’s proof. While trying to mimic the extreme conditions found deep beneath the Earth’s surface, a researcher turned one of the most popular sandwich condiments into a substance even more valuable, if less tasty: diamond.

Dan Frost, a research scientist at the Bayerisches Geoinstitut, University of Bayreuth, Germany, wants to know what’s going on in the Earth’s lower mantle, which sits 1800 miles below the surface and is somewhat of a mystery to researchers. We know it’s very hot (temperatures may reach 4000 degrees Fahrenheit) and under an incredible amount of pressure (237,000 times atmospheric pressure is a low estimate). We also know the mantle is where diamonds are formed. These precious gems are composed of carbon atoms that have been heated and squeezed and then pushed toward the Earth’s surface, where they cool. In trying to mimic the conditions of the mantle, Frost successfully created synthetic diamonds in a lab. His source of carbon? I’ll give you a hint: it pairs well with jelly.

He placed some peanut butter between two diamonds (this is called the “stiletto heel effect”) and compressed the nutty stuff. Why the diamonds? They’re incredibly hard, thanks to their closely-linked carbon atoms, and can withstand the necessary amount of pressure for the experiment, which is about 1.3 million times that of our atmospheric pressure.

The result is a diamond where a peanut used to be, albeit a paltry and not entirely pure one. “A lot of hydrogen was released that destroyed the experiment,” Frost told the BBC, “but only after it had been converted to diamond.”

This actually isn’t the first time this has been done. Researchers at Edinburgh University produced similar results back in 2007. "Many carbon-containing materials can be converted into diamond including peanut butter," said Edinburgh University's Malcolm McMahon. And diamonds are already manufactured synthetically, mostly for industrial use in producing grinding or cutting tools that benefit from the material’s hardness.

Frost hopes his experiments will lead not to cheaper diamonds, but larger knowledge about the inner workings of our planet. “If we want to understand how the Earth was formed, then one of the things you need to know is what planet is made out of,” he said.