Crater of Diamonds State Park

Crater of Diamonds State Park, near Murfreesboro, Arkansas, sits atop the eroded remains of a volcanic pipe roughly 95 million years old, the only diamond-bearing site in the world open to the public for digging. Its 37.5-acre plowed field is regularly tilled by rain and park staff to bring new stones toward the surface, and any diamond found belongs to the person who found it. The largest diamond ever discovered in the United States, the 40.23-carat 'Uncle Sam,' was found here in 1924, before the site became a state park in 1972. Thousands of smaller diamonds have been found by visitors in the decades since.