Over the years it has been said that diamonds formed from the metamorphism of coal. According to Geology.com, we now know this is untrue. “Coal has rarely played a role in the formation of diamonds. ... The diamonds form from pure carbon in the mantle under extreme heat and pressure.

How much pressure turns coal into a diamond?

Under the duress of approximately 725,000 pounds per square inch, and at temperatures of 2000 – 2200 degrees Fahrenheit, a diamond will begin to form. The carbon atoms bond together to form crystals under this high pressure and temperature.

Is compressed coal diamond?

A common misconception is that diamonds form from highly compressed coal. Coal is formed from buried prehistoric plants, and most diamonds that have been dated are far older than the first land plants.