Bobbie Oskarson, a Colorado native, found an 8.52 carat diamond shaped like an icicle Wednesday at Arkansas' Crater of Diamonds State Park in Murfreesboro.
According to park officials, the gem is the fifth largest diamond found since the park was established in 1972, CNN reported. It is about three-quarters of an inch long and as big around as a standard No. 2 pencil.
At first glance, Oskarson thought she had dug up a quartz crystal, but she realized that it was special after further inspection, 9 News reported.
After several scoops of dirt within 20 minutes, Oskarson found the diamond from a muddy area of the park and called it "Esperanza" after her niece's name, which means "hope" in Spanish.
The park has yet to provide the diamond's potential value. There are 75,000 diamonds unearthed from the park with a "finder's keepers" policy.
Park interpreter Waymon Cox said in a statement that Oskarson found the gem in the southwest corner of the 37.5 acre search field.
Dozens of people find diamonds in the park every year, but it is rare to find one as large as what Oskarson found. The largest diamond found at the park is 16.37 carats, discovered in 1975.