A court has ruled jewellery firm Tiffany could recover US$19.4m (€16.5m) in damages against a US wholesaler.
Costco has said it will appeal the ruling over the company's sale of engagement rings bearing the 'Tiffany' name.
Back in 2015, the US District Court in New York denied Costco's claim that 'Tiffany' is a generic term for a pronged ring.
It also found that Costco was liable for trademark infringement and trademark counterfeiting in its use of 'Tiffany' on signs in the jewelry cases at Costco to describe certain engagement rings that were not made by Tiffany.
Judge Laura Taylor Swain said Tiffany deserves US$11.1m (€9.4m), plus interest, plus US$8.25m (€7.0m) in punitive damages awarded by a jury last October.
Reuters reports she also permanently barred Costco from selling anything that Tiffany did not make as "Tiffany" products - unless it uses modifiers suggesting that the products have, for example, a Tiffany "setting," "set" or "style."
Tiffany had sued Costco back in 2013.
In a statement, Costco said it will appeal the ruling due to, what it claims are, "multiple errors in pretrial, trial, and post-trial rulings".
"The diamond ring in question had a pronged setting style that is commonly known as a 'Tiffany' setting.
"Costco intended that the word Tiffany in its signs convey only that the rings had this style of setting - not that the rings were Tiffany & Co. brand rings", Costco added.
Tiffany was founded in New York in 1837 and also has an Irish presence through Brown Thomas in Dublin.
Costco currently operates 737 warehouses, including 28 in the UK.