Costco Wholesale Corp willfully infringed Tiffany & Co’s trademarks by selling counterfeit diamond engagement rings bearing the luxury retailer’s name and must face a jury trial to assess damages, a U.S. judge ruled on Tuesday. U.S. District Judge Laura Taylor Swain in Manhattan rejected claims by Costco that Tiffany’s trademarks were invalid because they sought to prevent others from using the word “Tiffany” as a generic description of a type of ring setting. Instead, Swain said evidence established that Costco, the largest U.S.