That is a great link to the Arbenz -Osborne copyright case. I hadn't realised that there had been such controversy over use of the name.
Does your gun definitely have the crossed pistols logo, or could it be they are rather indistinct crossed rifles? The reason I ask is because Fritz Langenhan Gems had a crossed rifles logo, as in this advert:
The interesting thing is that the advert also has the name "Gem" written in a very similar style to the "Gem" on your box lid: