sentences:  In February 2013 Tiffany & Co. filed a trademark infringement lawsuit against Costco Wholesale Corp. over Costco's practice of selling prong setting engagement rings described as "Tiffany setting" rings.The lawsuit alleged that Costco was unlawfully using the "Tiffany" trademark to describe products that were not made or licensed by Tiffany & Co.In its defense, Costco asserted that it did not infringe because the terms "Tiffany" and "Tiffany setting" were genericized by common usage to describe prong setting engagement ring.