In 2014, scientists crushed a diamond and found a tiny blue clue to water deep inside Earth

Diamonds are famous for their sparkle on the outside, but their true scientific worth often lies within. A diamond sourced from Juína, Brazil, helped change our understanding of what lies beneath the Earth's surface. Upon crushing the diamond specimen, scientists found a microscopic blue speck that acted as a natural time capsule of the deep Earth.It is important to note that this particular inclusion proved to be ringwoodite, which is a unique type of mineral formation that forms only under the immense pressure of the deep mantle. It was determined that this was the first instance in which this high-pressure olivine polymorph was found in a naturally occurring sample originating from our planet rather than from a meteorite. Thanks to the fact that the inclusion was encapsulated in the diamond, it could retain its structure all the way up until it came to the surface.Crucially, this particular mineral provided scientists with another exciting piece of information. In fact, after conducting a series of tests, it became evident that the presence of the mineral pointed to structurally bound water far beneath the solid crust of the Earth.Unlocking a microscopic capsule from the deep mantleThe exact chemical and structural details of this find were reported in a 2014 study published in the journal Nature, titled Hydrous mantle transition zone indicated by ringwoodite included within diamond. Led by a team of international mineral experts, the research explained how multiple analytical tools were combined to look inside the microscopic gem. The team used precise X-ray diffraction along with specialised laser spectroscopy to map out the crystal pattern without destroying the sample.A later Gemological Institute of America review noted that the blue inclusion was only thirty micrometres wide. In spite of its small size, the mineral remained intact within its high-pressure form due to the fact that it could not expand when rising because of the surrounding diamond matrix. Due to such natural protection, the scientists were able to examine an otherwise unreachable layer of our planet’s interior.The most significant data was obtained by testing the absorption of infrared radiation through the crystal, which revealed a water-rich signal. The researchers' experiment concluded that their sample had about one per cent of water content structurally bound within the crystal's matrix. While one per cent might sound small, the detection of this moisture level in a solid sample suggests that the mantle transition zone can hold water locked directly into the molecular configuration of rocks in the deep interior of the planet. Rethinking the inner layers of the planetIt became clear that when discussing the water cycle of the Earth, scientists could move beyond purely theoretical computer modelling techniques, relying instead on the concrete facts presented by the new research. The detection of water-rich ringwoodite means that the mantle transition zone, which is located roughly 410 to 660 kilometres below the surface, is able to keep structurally bound moisture.It is important to clarify the fact that finding evidence of water in this zone does not imply the existence of underground oceans or lakes of liquid water. The water is entirely held within the structural lattices of highly pressurised minerals and is an integral part of the rock in solid form. Nevertheless, since the deep transition zone is immensely vast, even a small percentage of structural moisture represents a significant volume of water hidden deep underground.While a single microscopic sample cannot prove that the entire interior of the globe is uniformly wet, it provides a vital benchmark for research into how our planet retains its elements. The crushed Brazilian diamond showed that parts of the deep Earth can store water inside minerals and move water across vast stretches of geological time. By staying close to the physical evidence, a tiny blue speck has given us a remarkably clear window into the hidden mechanics of the world we live in.