Curious - What's this small circular ink-stamp found on back of a $50 USD banknote?
Apologies if not an appropriate topic within the Currency Forum.
In my wallet, far more likely to come across a $1 bill, so am familiar with a "Where's George" stamp. But when checking the security features on an older larger denomination bill (2001 series) which had been handed to me, noticed an unfamiliar stamp on the reverse side. Circular format, blue-ish ink, diameter about 1cm. Curious what it is. (Photo is oriented as when viewing the banknote normally.)
At least with the search terms used, online results included only stamped text (political/economic opinions), and a set of stock photos depicting a couple of other stamps on US currency - for sale on a commercial website, which presumably should not be linked here. (For clarification, though, a search engine queried with "closeup american cash banknote marked inked symbols red blue" should find those photos.)