Molten carbon can form into either diamond or graphite. A new study shows how graphite can sometimes form even under conditions that should lead to diamond. (Getty Images) The graphite found in your ...

(CNN) — A layer of diamonds up to 18 kilometers (11 miles) thick could be tucked below the surface of Mercury, the solar system’s smallest planet and the closest to the sun, according to new research.

The graphite found in your favorite pencil could have instead been the diamond your mother always wears. What made the difference? Researchers are finding out. How molten carbon crystallizes into ...