Wow, what a great piece! Where did you find it?
My vote is Diana/Artemis, definitely.
It's intaglio engraved. I don't see any etched areas, and would be surprised if there were any.
Czech/Bohemian is my guess. The Bohemians seem to have an affinity for mythological images in their engravings. The shape of the blank is right, too. Kind of reminds me of this tumbler, if only because of the subject matter:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=330230350505Is there water in it? Ordinarily I wouldn't expect much distortion or magnification, although taking close photos can have that effect.
I tried the rice trick for the first time a couple weeks ago, where you put a bit of water and some raw rice (and cleaner, if desired) in the glass and swirl it around vigorously. It worked surprisingly well. Maybe you've tried that already. Good luck getting it clean, and I hope it's not sick. It seems like Bohemian glass isn't as prone to crizzling as some others.