We Reveal the Volcanic Secret That Helps Diamonds Blast to the Surface Intact

Scientists have just revealed a sparkling new twist in the story of how diamonds make their extraordinary 90-mile journey from deep within the Earth to the surface. It's well known that these gems don’t travel alone — they hitch a ride inside a rare, gas-charged magma called kimberlite. Think of it as Earth’s own diamond delivery service… but one that only works if the recipe is mixed just right.

New modeling — highlighted this month by Earth.com based on research published in Geology — shows that kimberlite magma must contain at least 8.2% carbon dioxide, plus a good helping of water, to stay buoyant enough to rocket upward. Without that crucial dose of dissolved CO2, the magma becomes too dense, stalls deep underground, and the diamonds never see daylight.

Here’s the fun part: dissolved carbon dioxide and water act as secret “lift” ingredients. They make the magma lighter than the solid rock around it, allowing it to rise quickly — very quickly. Scientists say the ascent must happen within hours, not days, or the diamonds will begin to change back into graphite, the soft carbon form that’s stable at shallow depths. In other words, if the kimberlite elevator doesn’t whoosh upward fast enough, those precious crystals lose their sparkle before the ride even ends.

As the magma rises, its dissolved gases expand dramatically, creating explosive, champagne-like bursts that carve out deep volcanic pipes. These structures — called kimberlite pipes — are the primary source of the world’s mined diamonds. The new research, led by Ana Anzulović of the University of Oslo, found that only when kimberlite is richly loaded with CO2 and water can it power through the crust-mantle boundary, a geological “gatekeeper” that stops slower, denser magmas in their tracks.

If the volatile levels aren’t high enough? No eruption. No pipe. No diamonds. It’s a high-stakes recipe where even a small mismeasure means the gems remain hidden forever.

But when the chemistry is perfect, kimberlite becomes the ultimate express elevator — lifting diamonds from 90 miles down and delivering them, intact and sparkling, to the surface in explosive style.

Credit: Russia's Mir mine in Mirny, Yakutia. Photo by Staselnik, CC BY-SA 3.0, via Wikimedia Commons.