MURFREESBORO, Ark. (AP) - A man visiting a diamond park with his fiancee found a 3.92-carat white stone, but it's not going to go onto the finger of his betrothed.

That's because she already has a ring - albeit only 1 carat - with a setting.

Eric Blake, 32, of Appleton, Wis., spotted the stone Tuesday along a trail at Crater of Diamonds State Park when he set down a bucket of mud he was carrying to a wash basin.

"I put the bucket down to switch hands. I looked down and there it was," Blake said.

The stone is big enough to fashion into jewelry, but Blake said Tuesday that he hadn't decided whether to have it placed into a setting.

His fiancee, Susan Gabrielson - who has "only one carat on her finger" - accompanied Blake to the park this week.

Crater of Diamonds is the world's only diamond-producing site open to the public, and visitors can keep the stones they dig up.

The largest diamond ever found in the United States, a 40-carat white stone named Uncle Sam, was unearthed there in 1924.