Tiffany & Co. ( NYSE: TIF ) is widely thought of as the king of high-end jewelry. While many local high-end jewelry stores compete with Tiffany in local markets, it is hard to imagine that Costco Wholesale Corporation ( NASDAQ: COST ) is a real destination for ultra high-end jewelry. The reality is that Costco has had many higher-end offering through the years but it is hard to imagine that you can spend $100,000 or $300,000 or even over $400,000 for diamond ring made of platinum at the box-store giant.