For those curious ...
... diamonds are not free at Crater of Diamonds State Park; there is a daily fee for visitors to enter the search area. The fee is currently $15 for adults and $7 for children, while children 5 and under enter for free. Visitors who find diamonds are allowed to keep them, following the park’s “finders, keepers” policy.
Jeez, that’s almost free, considering you get to keep the diamonds.
THAT IS A CHEAP DAY LONG ENTERTAINMENT, IMO.