On Thursday, Tiffany (TIF) announced that it has filed suit in the U.S. District Court for the Southern District of New York against Costco Wholesale (COST -0.32%), alleging "trademark infringement, dilution, counterfeiting, unfair competition, injury to business reputation, false and deceptive business practices and false advertising."

Specifically, Tiffany says the warehouse superstore has sold, and may still be selling, "counterfeit diamond engagement rings" under the Tiffany brand name. Tiffany is seeking injunctive relief (i.e. a court order forbidding Costco from conducting such sales) as well as damages compensating Tiffany for lost profits from sales that have already occurred.

"Tiffany has never sold nor would it ever sell its fine jewelry through an off-price warehouse retailer like Costco, either directly or indirectly," wrote the company in its press release.

According to the press release, Tiffany first learned that Costco might be selling rings using its name from a tip by a Costco customer in November of last year. It said it later learned such had apparently been happening for "many years." 

In 2004, Tiffany filed a similar lawsuit against eBay, claiming the online auction house allowed users to sell on its site knockoff Tiffany jewelry. In that case, Tiffany managed to assemble a trove of 186 "Tiffany" items sold on the site before filing suit.

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