GENEVA – The Fortune Pink diamond, an exceptionally rare giant gemstone, sold for more than $28.5 million at auction in Geneva on Tuesday to a private Asian collector. At 18.18 carats, the gem is the largest pear-shaped “fancy vivid pink” diamond ever sold under the hammer, Christie’s auction house said. The dazzling diamond fetched a hammer price of 24.5 million Swiss francs ($24,615,150), rising to 28,436,500 Swiss francs ($28,570,150) with the buyer’s premium added on. The bidding, which lasted for a tense four minutes, started at 17 million Swiss francs and was a three-way battle between t…