I posted in another forum, and some very helpful people said that it was German, hallmarked in Berlin, but that was all they could tell me.
I have researched the Berlin mark as thoroughly as I can, and right now, I'm getting a date of between 1700-1740. Before 1700, the mark was a bear in a CIRCLE, and after 1745, the mark was bear in an OVAL, but with a letter, which mine does not have. I wanted to know if I was correct? Is there any way to date it more precisely?
I also wanted to know if anybody here can decipher the purity mark? It's the only other mark on the cup and I can't read it. I know what it's SUPPOSED to look like, but...eh.
It will be a number between 12-15, and it indicates the grade of silver, according to the old German system. Anywhere from 750-930 or something like that.
Anyway. Enough babbling. Here's the cup and such...

Marks.
Cup:

300 years, give or take, and it's never been engraved...

Inside, and underside:





