But the new results are unlikely to set off a diamond rush.
Cratons are the oldest sections of rock beneath that usually lie beneath continental tectonic plates, and their roots - shaped like inverted mountains - stretch up to 200 miles beneath the Earth's surface.
To estimate the total mass of diamonds in the Earth, the researchers assumed cratonic roots were 1-2% diamond and combined that with the total volume of cratonic roots distributed throughout the Earth.
Scientists have found evidence to suggest that a thousand trillion tons of diamonds are buried deep in the Earth's crust.
"Diamonds are a ideal match because they're a little bit more dense, but we don't need a lot of them", said Ulrich Faul, a researcher in MIT's Department of Earth, Atmospheric, and Planetary Sciences and a senior participant in the study.
'We can't get at them, but still, there is much more diamond there than we have ever thought before'.
The study, which was published in Geochemistry, Geophysics, Geosystems, looked at some curious behavior of sound waves traveling through the Earth deep underground. Then, the worldwide science team managed to calculate the differences in the speed of sound waves as they passed through different combinations of rocks and minerals.
Don't tell the Hatton Garden gang: scientists just unearthed an eye-watering hoard of diamonds, so valuable it would completely destroy the world's economy. Then we have to say, There is a problem.
Sound travels through diamond twice as fast as other rocks, so the team of researchers figured there had to be some of the material in the cratons. This is atleast 1000 times more diamonds than they expected.
Parts of Earth's mantle may be up to two percent diamond by composition, far more than previously suspected. They arrived at the conclusion that if these structures contain between 1 and 2 percent diamond, then the speed of the seismic waves makes sense.
'Cratons are a tiny bit less dense than their surroundings, so they don't get subducted back into the Earth but stay floating on the surface.
Faul, who worked in the lab with a team of seismologists, geochemists and other scientists, slightly increased the amounts of diamond in the virtual rocks, until they reached a combination that produced the same advanced speeds they'd been encountering by using seismic technology on the real Earth. The deepest parts are referred to as "roots" by geologists. The anomaly in the data was that sound waves sped up as they went through the roots of old cratons. So we found that you just need 1% to 2% diamond for cratons to be stable and not sink.
Diamonds fetch their lofty price tags because they form over millions of years under high pressures and temperatures deep within the Earth's crust.
"We went through all the different possibilities, from every angle, and this is the only one that's left as a reasonable explanation", Faul said.