You may have noticed finding something called "an Imperial dira" in a treasure. Looking at it tells you it's an old coin from the days of the Seven-Star Empire bearing the image and dates of one of the emperors. If you have a suspicion that some of these might be -very- old and perhaps -very- valuable, you may be right!
It makes sense to think that the older the coin, the more valuable it might be, but what do pawnbrokers know? They're not numismatists! You will be able to pawn the diras, but don't expect a knowledgeable appraisal at a pawnshop.
Check out the Coins of the Realms shop in Shard for collectors cases and money-making opportunities!