Denis Tyrrell was walking past a hole he'd filled in while searching for gems at Crater of Diamonds State Park, when he saw a sparkle. The 3.48-carat diamond turned out to the biggest that diamond Tyrrell had found in regular digs that he began in March. The stone is also the 1,000th diamond found at the park this year, a mark last reached in 1994, park interpreter Kim Garland said Monday.