Sotheby’s sold a 59.6 ct pink diamond for about $71-million in Hong Kong, setting the world record for the top auction price for any gem. The stone has an an unusual distinction: it has attracted even higher bids in the past. Hong Kong-based jewelry retailer Chow Tai Fook had the HK$553-million winning bid for the Pink Star after a five-minute contest that included three phone bidders, Sotheby’s said Tuesday. The oval-shaped diamond dethroned the Oppenheimer Blue, which fetched $58-million in May at Christie’s.