I didn't know about the Will Columbia- good call. However, I had a look in the Blue Book and it says that some of the Eisenwerke Gaggenau imported Columbia air rifles were actually stamped with that name, suggesting that the name might be a genuine EG factory name. If so then I guess they would predate the Will Columbia by several years?

I have had second thoughts about the Gems and think that it was a generic name coined by Arbenz for his UK imported EG air rifles, and not a factory name from EG. Could be wrong though.

Big Bertha? You are joshing me?