I've had this chip since 1993 and never found an ID. Carlos in Portugal finds nothing, either.

It was a gift back then from someone in the casino business in Portugal and the note with it read: "...from a 1920's private Club Atlantico to the north..."

I post it here every couple years in hopes that someone knows something, but thus far, nothing.
It was once listed in TGT; my entry, but no longer.