The Crater of Diamonds

The only diamond-bearing site on Earth where the public can dig and keep what they find, no questions and no share. It is the eroded surface of a lamproite volcanic pipe in Arkansas, ploughed periodically by the state park, and visitors have taken more than 35,000 diamonds off it since 1972, including the 40-carat Uncle Sam, the largest ever found in the United States. Most finds are small, and rain is your friend: it washes the field clean and diamonds sit on the surface with a distinctive greasy shine. Modest daily fee, bring a bucket and knee pads.