Hiker finds 4.38-carat diamond in US park, is hers to keep

Diamond in the rough: The park is one of the few places in the world where the public are free to prospect for diamonds. Photo / Supplied, Arkansas Park Services

If you needed a little motivation to head outdoors, how's a 4.38-carat diamond?

A woman hiking in Arkansas State Park has pocketed a rare gem worth over $22,000, according to the park service, and it's hers to keep.

Noreen Wredberg of California was exploring the Crater Diamonds State Park on 23 September when something bright and brilliant yellow caught her eye.

"I didn't know it was a diamond then, but it was clean and shiny, so I picked it up," she said in a park press release.

A couple of hours' drive outside - the appropriately named - Little Rock Arkansas, the area attracts visitors from all over the world.

Around fifty diamonds are discovered every year in the park but most of the stones discovered are semi-precious quartz or garnets, which can be easily mistaken.

Noreen Wredberg's discovery was confirmed by the park as a 4.38 carat diamond. Photo / Supplied, Arkansas Park Services

Wredberg and her husband Michael didn't believe their luck until the park's Diamond Discovery Centre confirmed what they had was a flawless, yellow diamond.

"We really didn't think we would find one, let alone something that big!"

Park Superintendent Caleb Howell recorded the find of a 4.38 carat stone as "about the size of a jellybean, with a pear shape and a lemonade yellow color."

The Wredbergs are thrilled by the discovery but are in no rush to get it valued.

The price of yellow diamond ranges hugely, depending on the quality of the stone, according to USA Today.

Per carat a fine yellow diamond can range from $3600 to $28700. One of the largest stones found in the past five years, Wredberg's find could be worth over $22000 and is hers to keep.

Wredberg's yellow diamond was about the size of a jellybean. Photo / Supplied, Arkansas Park Services

As the name suggests the park is a famous diamond fossicking in the crater of an old volcano and one of the few places in the world where the public can find precious stones on the earth's surface. The 15 hectare park attracts visitors from all over the world, according to Park Services.

Powered mining tools or excavation is not allowed, but should you come across a diamond in the rough, it is yours.

The largest discovery was made in 1972, a 40.23-carat called Uncle Sam, the largest diamond ever unearthed in America.