That doesn't mean it isn't cool. Until now, it was generally thought that diamonds required complex chemical reactions called redox reactions (reduction and oxidation) involving the loss and gain of electrons as different kinds of fluids move through rock. But according to the new study, simple changes in pH (or acidity) can spur diamond formation, too.
The new model suggests that at very high temperatures (over 1,650 degrees Fahrenheit) and high pressures (over 725,000 pounds per square inch), water can form diamonds naturally as it moves from one kind of rock to another. The key is the natural drop in pH — the water getting more acidic.
If these diamonds are forming, they're forming around 100 miles below the surface. That's more than 10 times deeper than any drilling exploration has ever gone. So the scientists involved in the study will most likely never get to see these diamonds in the flesh.
But the researchers hope that their model can be used to study wider interactions between deep fluids and rock, helping other scientists to better understand the way our Earth's interior has evolved over time.