Crater of Diamonds State Park in Murfreesboro, Arkansas, offers a rare opportunity where amateur prospectors can search for real diamonds and keep them. Since the park opened in 1972, more than 37,000 diamonds have been found, including notable gems like the 40.23-carat "Uncle Sam" diamond. The park is the only diamond-producing site in the world open to the public, where visitors pay an entry fee and can search over 37 acres of plowed field, the eroded surface of an ancient volcanic crater. Finds are frequent: on average, two diamonds are discovered each day. The park provides identification and certification services for any gem found.