Diamond Dov (real name unknown) is an Israeli celebrity jewelry designer whose ring was found in the murder investigation of Caroline Pereira. Pereira won the ring in a gambling ring from football star Roddy Franklin, the first owner who was a regular at Diamond Dov's shop.
When the make of the ring was traced to Diamond Dov, detectives personally went to his jewelry store, threatening with inspections if their questions weren't answered. Diamond Dov directed the detectives to Franklin, who helped detectives find just the motive for Caroline's murder, and eventually the killers. (SVU: "Class")