Interesting new addition. (Edited with better photos)

Here's an interesting little oddity I picked up last week. It's glass, quite heavy for its size and although a little worn, is a nice addition to my collection. I really can't figure out what it is. A paperweight, perhaps? If anyone has any thoughts, I'd appreciate the feedback.
Edit: After asking a friend in the UK, he's convinced it's a paperweight but I''m still open to other suggestions.