Diamond Zero

This is how it works: In nature, the heat and pressure of the earth turns coal into diamonds over a period of thousands of years. Industrial diamonds are created by processing coal in a machine that mimics the heat and pressure of the earth. Because coal is the carbonized remains of prehistoric plants and animals, it is made up of the same chemical components found in all other organic life forms, including human beings, so, what would happen if cremated human remains were used instead of coal?