I made a small investment today (just for having a confirmed ID here on the board), and bought the first labeled one of these unidentified vases -- after having seen appr. 30 to 40 of them without label during the last years: it is Walther Glas, Germany

I still wonder why they are that abundant here in Austria, and not so in Germany...
Most come in this grey colour, but I have seen them in amethyst and yellow, too.
Michael