Hi! I'm Eduardo, the owner of the coin, I opened a profile here just to say hello.
I haven't sold the coin. Though counterfeit, I've become attached to it somehow, due to its provenance and because I've learned a lot of interesting things just by trying to find out what it is. Times are a bit rough, though, and I may do so later.
Herr Dicker's thesis regarding a possible movie-worthy background story to the coin is indeed fascinating, and so I hesitate to mention that I am not of German extraction, I hold a Spanish passport and I am headquartered in ... Sheffield. I just travel a lot. As for my grandfather's contacts, I'll have to ask my mother whether she remembers any of them having funny accents.
Seeing as how I am now famous (!) maybe I should contact St. James Auctions...the coin may be counterfeit, but it's good gold, and on top of it, there's a story!
I've got more pictures if anyone wants to see them.
Thanks to Herr Chard for the help.