The shape is very similar to the German Peill & Putzler Eos vase (70s I suspect), but this is obviously not a vase. I think in the same period they made drinking glasses Kegel-ex that were meant to be placed upside down and then looked like bowling pins (they obviously couldn't be put down with liquid in them).
Maybe they used the same idea with the Eos pattern, and this is meant to be a drinking glass that could also be stored upside down? But I have no idea if any drinking glasses were made in the Eos pattern, and whether I'm on the right track here. If it's a drinking glass, it may not have the normal Peill & Putzler etchmark.
I wish I could post a link, but my only source is a book, can't find an online example of the Eos. But even if this is something else, Germany might be a place to look for.
Astrid