A tiny gemstone from Brazil has provided new, compelling evidence that water may penetrate much deeper into Earth’s interior than previously believed. One standout mineral found within the diamond is goethite, an iron-rich mineral commonly found on Earth’s surface and responsible for the brown hues in many soils. Notably, goethite contains water within its crystal structure, leading scientists to believe it could play a significant role in transporting water into Earth’s depths. One particular inclusion was surprising because it appeared to contain iron hydroxide — a mineral rarely expected to be found inside Earth’s mantle. Beyond revealing the extraordinary journey of this tiny gemstone, the findings shed light on how water moves through Earth’s interior—potentially more interconnected with surface water cycles than previously understood.