"Took it off a goblin body," explains Elyra.
"I've not seen it's like before. The best I should be able to say is that I suspect a private minting, and for ill gain. Since you took it off a goblin body, perhaps someone's used a cunningly weighted slug to buy the services of the intruders? Troubling, that..." Sir Korvaski trails off in thought, obviously perturbed by where his thoughts lead.
Sir Jasper frowns and pauses. "I shall alert the Mercantile investors and shall post public billboards about town--it's to be hoped that the coins don't find their way into local circulation. Aye, that would indeed be troubling."