Sotheby's to Auction Rare Diamond in Hong Kong HONG KONG - China's economy is cooling, and Asia's once-rosy prospects look less shiny than they did two years ago, but this has not deterred Sotheby's from choosing Hong Kong as the place to sell a rare multimillion-dollar diamond in October. The auction house is expected to announce on Monday that the stone, "The Premier Blue," will be sold on Oct. 7 as part of Sotheby's regular twice-yearly auction series. The stone weighs 7.59 carats and is about the size of a shirt button. Its size, vivid blue color and round-cut shape - highly unusual for colored diamonds - make it exceptionally rare, and Sotheby's expects the stone to bring about $19 million, Quek Chin Yeow, deputy chairman of Sotheby's in Asia, said in an interview before Monday's announcement. That, he said, would be a record per-carat price for any diamond. The choice of Hong Kong as a place to sell the stone underlines just how important Asia has become as a consumer of luxury items, as rapid growth has swelled the ranks of the ultrarich. "Since about 2006, 2007, Hong Kong has ranked alongside Geneva and New York as a center for jewelry sales," Mr. Quek said. It is now the third pillar of the global jewelry market. That the rapid growth has slowed has generally not dented the ability and willingness of these superrich to spend. The rich generally remain rich even when times are worse, luxury industry analysts said. Moreover, Mr. Quek said, Asian buyers tend to be more willing than their Western counterparts to seek out buying opportunities during uncertain times, often making purchases with an eye to potential price rises down the line. And when it comes to diamonds, they tend to like round cuts and colors - another reason for choosing to auction The Premier Blue in Asia rather than in Europe or the United States. Sotheby's is previewing the stone and other auction items around Asia, including in Beijing, Shanghai, Bangkok, Singapore, Jakarta and Taiwan - a reflection of the regional spread of buyers. About 25 percent to 30 percent of the money spent at the Hong Kong art and jewelry auctions comes from mainland Chinese buyers, but Hong Kong buyers are also very active, as are Singaporeans, Indonesians, Taiwanese and southeast Asians, Mr. Quek said.