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).
In the U.S., diamonds have been found in Arkansas, Colorado, Wyoming, and Montana. In 2004, the discovery of a microscopic diamond in the U.S. led to the January 2008 bulk-sampling of kimberlite pipes in a remote part of Montana.
3. Excelsior Diamond: 995.20 carats. Found in 1893 in South Africa, this huge rock was cut into many smaller pieces. The largest gemstone cut from this famous diamond was only 69.68 carats, but many in the diamond industry believe that much larger diamonds could have been taken from the original stone.