Why would a consumer spend thousands more to buy a stone at Tiffany’s?

A recent study indicates that a variety of retailers sell one-carat diamonds, but consumers pay vastly different prices at Costco versus Tiffany’s. The diamonds are a commodity; they must meet the same standards and are rated the same. Why would a consumer spend thousands more to buy a stone at Tiffany’s? MUST BE DETAILED… NO PLAGIARISM. 3 PARAGRAPHS.