The Crater of Diamonds State Park in Murfreesboro, Arkansas allows visitors to dig for and keep any diamonds found on the premises in exchange for a fee. It is the only diamond mine in the world open to the public, as of 2015.
The Crater of Diamonds State Park sits over a volcanic pipe responsible for the formation of the diamonds and gems in the area. The state of Arkansas purchased the site in 1972 and developed it into a park consisting of 888 acres, a visitor's center, gift shop, picnic area and restaurant. The visitor's center contains exhibits and programs providing information on the geology and history of the area, as well as providing tips on ways to search for diamonds. The park also contains trails and campsites. Visitors search for diamonds on a 37-acre plowed field above the volcanic pipe. Geologists believe the Crate of Diamonds State Park is the eight largest diamond mine in the world.
Visitors can find white, brown and yellow diamonds in the State Park, and park staff offer identification and certification of any found diamonds for free. Other gems visitors may find in the park include amethyst, garnet, jasper, agate and quartz.
Since its opening in 1972, visitors have discovered over 19,000 diamonds. The biggest diamond found in the park is called the Uncle Sam, a 40.23-carat diamond that was found in 1924.