A California woman visited the Crater of Diamonds State Park in Arkansas where she accidentally found a 4.38-carat yellow diamond, one of the rarest diamonds.

Arkansas State Parks officials say Noreen Redberg, a Granite Bay woman, was visiting the park with her husband on Thursday and spent about 40 minutes searching for jewelry in the open field when she came across something shiny on the surface.

“I didn’t know it was a diamond, but it was clean and shiny, so I picked it up,” she said.

The woman’s husband took her to the Diamond Discovery Center, where she identified a 4.38-carat yellow diamond.