Thanks Ivo. That's a pretty unusual shape vase and rather nice8) .
My blue one is very similar to a red one I had some years ago. It had the same highly polished multi-faceted sides and heavy crystal base, but that one was simpler in design with just plain vertical sides. At the time I spotted an identical one to mine on a reputable website, attributing it to Ilmkristall, so I figured mine was too. My current blue vase bears all the same hallmarks as the other one and I just felt that it too was Ilmkristall.
I've spotted the odd one since on eBay but never with an attribution.