A man posing as a customer in a mall jewelry store grabbed a $100,000 diamond ring and ran off as the salesman chased him.

Police found a car the man was believed to have fled in, but it, too, had been reported stolen, Upper Merion Township Police Sgt. Jeff McCabe said.

No arrests had been made Wednesday morning. Police hoped to identify the suspect through fingerprints and security surveillance tapes. The store tape of the weekend theft shows the man examining the ring for several minutes at Milanj Jewelers in the King of Prussia Mall, just outside Philadelphia, then running off.

The man had asked to see a three-carat diamond in a platinum setting, police said.