The most expensive jewel ever sold was auctioned off Tuesday, fetching $71.2 million at a Sotheby’s auction in Hong Kong. The plum-sized Pink Star, a whopping 59.6 carat pink diamond, was snagged by Hong Kong-based jewelry retailer Chow Tai Fook after a five-minute bidding war. The Pink Star diamond was the largest internally flawless, fancy vivid…