Crater of Diamonds State Park is a 911-acre (369 ha) Arkansas state park in Pike County, Arkansas, in the United States. The park features a 37.5-acre (15.2 ha) plowed field, the world's only diamond-bearing site accessible to the public.

Diamonds have continuously been discovered in the field since 1906, including the Strawn-Wagner Diamond. The site became a state park in 1972 after the Arkansas Department of Parks and Tourism purchased the site from the Arkansas Diamond Company and Ozark Diamond Mines Corporation.

Arkansas’s Crater of Diamonds State Park is one of the only diamond-producing sites in the world where the public can search for diamonds in their original volcanic source. The policy here is "finders, keepers," meaning the diamonds one finds are theirs to keep.

Visitors search for diamonds atop a 37 1/2-acre plowed field, the eroded surface of an ancient, diamond-bearing volcanic crater. The diamonds at the Park occur in the soil, and that makes them easy to look for. Some people find them after it rains by walking through the field looking for the bright reflection of a diamond that has been washed clean by the rain.

More than 33,100 diamonds have been found by park visitors since the Crater of Diamonds became an Arkansas state park. Notable diamonds found at the Crater include the 40.23-carat Uncle Sam, the largest diamond ever unearthed in the U.S.; the 16.37-carat Amarillo Starlight; the 15.33-carat Star of Arkansas; and the 8.52-carat Esperanza.

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