How Do Diamonds Form?
Contrary to what many people believe, most diamonds do not form from coal.
Article by: Hobart M. King, Ph.D., RPG
Diamond formation
Diamond formation: Diamonds found at or near Earth's surface have formed through four different processes. The plate tectonics cartoon above presents these four methods of diamond formation. Additional information about each of them can be found in the paragraphs and small cartoons below.
Methods of Diamond Formation
Many people believe that diamonds are formed from the metamorphism of coal. That idea continues to be the "how diamonds form" story in many science classrooms.
Coal has rarely played a role in the formation of diamonds. In fact, most diamonds that have been dated are much older than Earth's first land plants - the source material of coal! That alone should be enough evidence to shut down the idea that Earth's diamond deposits were formed from coal.
https://geology.com/articles/diamonds-from-coal/
