What happens when a product reaches a level of ubiquity so prevalent that it becomes representative of both itself and its competitors, regardless of origin or manufacturer? Take for example Coca Cola: in certain areas of the country, "a Coke" is a catch-all term for any soft drink, even though that particular beverage is but one of many available to consumers. As trademarks go, however, Coca Cola has no grounds to take any sort of action against any of its competitors, because none are selling their drinks using the Coke name; rather, it's a term that has grown organically and is used colloquially. What happens when such terms enter both the lexicon and marketing materials?
Costco and Tiffany & Co. may seem strange combatants in a trademark scuffle, but the case in question goes some way in clarifying the use of terms originating from a single entity that become an industry standard. In this case, Tiffany sued Costco over rings the retailer was marketing as "Tiffany" rings and won a summary judgment of nearly $20 million, including damages. And to the layperson, that would seem a fair result, given a cursory reading of the facts and a minimal knowledge of jewelry beyond its often considerable expense.
However, as Techdirt lays out, there is more to the case and the use of the Tiffany name than that, which is why Costco won its appeal to have the judgement overturned. Tiffany is the name of a famous jeweler, and itself a trademarked brand, but it's also the creator of a ring setting so prevalent that it has its name attached to it across the industry. As Geigner notes, the "Tiffany setting" has become so generic after over a century of use that any and all trademark concerns essentially become null and void, at least as far as that aspect of the brand name. In this instance, Costco can reasonably make the case that it was simply using an industry term to describe the setting of the rings it was selling and not attempting to mislead customers as to the manufacture of the ring.
While it's understandable that Tiffany & Co. wants to preserve its brand and reputation, it's worth wondering why they chose to pursue a case on rather specious grounds, given that there's not much to the case itself. If the "Tiffany setting" is in fact an industry-wide term and there's no real argument to be made for consumer confusion, what's the case? Although, in pursuing a case based not on legal considerations of trademark use but on a dislike of how the name is used, Tiffany is not alone among big brands.