Eight-year-old twins find costly raw diamond in US state park Mon Mar 12, 1:30 PM MIAMI (AFP) - A couple of eight-year-old twin boys have found a 2.50 carat raw diamond that could be worth thousands of dollars, according to the director of a state park in the southern US state of Arkansas. "They thought it was a piece of mica. When they learned it was a diamond, there were many 'woo hoos' and high-fives exchanged," said Rachel Engrecht of the Crater of Diamonds State park. She said the children found the 2.50 carat diamond during the weekend in the park, where visitors are encouraged to prospect for the precious stones. Another park official, Bill Henderson told AFP on Monday the gem could be worth several thousands of dollars. He said the stone, named the "Duncan twins" after its young boys who found it, has a sparkling metallic look and is "almost heart shaped."