Hi Sue, I was intrigued to see your photo of this solifleur vase as I have one very similar, with no label, though mine is slightly smaller, more like 4.5” by 4.5”.
Mine was sold to me as “made by either Pukeberg or Skruf Glass” but I don’t think it is, mind you I am not an expert! I have a collection of 3 different height rectangular solifleur vases by Ingrid Glass (2 of which are labelled IG Ingridglaeser Blockkristall Zweigvase)) which have an identical type of pattern, the colour of the glass matches, in fact I have them all on display together as they go together perfectly.
I also have a number of solifleur vases by Walther but this one does not “match” and looks out of place when they are put together.
I know this isn’t the positive identification you are looking for. I will be watching this post to see if anyone can confirm the maker.