SCIENTISTS REVEAL THE SECRET BEHIND THE LARGEST DIAMONDS ON EARTH
You don’t have to be in the diamond business to recognize names like the Cullinan, Constellation, and Koh-i-Noor – some of the rarest, most expensive and captivating diamonds ever discovered on Earth. Now, scientists from the Gemological Institute of America (GIA), led by gemologist Evan Smith, have published an article in Science magazine tracing the origins of these extraordinary stones.
The Cullinan Diamond, the largest rough diamond ever to have been discovered ( 3106 carats, the equivalent of 621 grams), and other extra-large diamonds, Smith said in a statement, “have characteristics that aren’t quite the same as other kinds of diamond. For years, geologists have wondered if maybe they formed in a slightly different way or if they came from a different part of the mantle. It’s been a lingering question that’s been really hard to tackle”.
According to the research, the most striking fact about large diamonds is their origin. According to Science Magazine, Smith and his colleagues “probed mineral inclusions from these very large diamonds and found abundant slivers of iron metal surrounded by reducing gases. This suggests that the large diamonds grew from liquid metal in Earth’s mantle”.
Most diamonds, about 98% of them, are formed approximately 150 to 200 kilometers inside the Earth. However, Smith et al. determined that large diamonds, including the Cullinan, Constellation, and Koh-i-Noor, come from the convecting mantle – located about 360-750 kilometers inside the earth. “This is far deeper than where common diamonds form”, Smith said. “At this depth Earth makes ¬diamonds to a different recipe, so they grow very pure and large”.