Thermoplastics, in basic terms, are melt-processable plastics (materials that are processed with heat). When enough heat is added to bring the temperature of the plastic above its melt point, the plastic liquefies (softens enough to be processed).
Where diamonds are found in the United States - Wyoming. Diamond Kimberlite pipes have been found in Wyoming, near the Colorado-Wyoming state line area referred to as the Aultman, Ferris and Schaffer kimberlites. The Herkimer Diamond Mine and the Ace Of Diamonds Mine - New York.
Diamonds can form in most of Earth's interior but not near its surface, where graphite is the stable form of carbon. Indeed, diamonds only survive at Earth's surface because great heat is required to break down the diamond structure.