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.
A partial list of famous diamonds in history follows. Name Uncut weight (carat) Cut weight (carat) Color Country/region of origin Description Image 26th Congress of the Communist Party of the Soviet Union 342.57 yellow Russia / USSR Mined at the Mir kimberlitic pipe (Yakutia, Russia) in 1980. It is the largest gem diamond ever found in Russia or the former USSR.