Steve Vehige found a 2.05-carat brown diamond at Crater of Diamonds State Park in Arkansas.
He was on his fourth visit to the park when he spotted the marble-shaped diamond on Saturday.
He's calling his gem the "Flint Hill Special," after his hometown and the song by Lester Flatt and Earl Scruggs.
So far this year, visitors have found more than 325 diamonds at the park.
The Flint Hill Special is the third weighing more than two carats found in 2013.