I'm adding this in a fresh post rather than editing my previous reply (above). In going back over the thread that I linked to, I noticed something I didn't see previously, and that was a link that Della gave to an old thread where Cathy Bannister had posted about her Melon Rib vases. (Della - I think I must have skim read the posts and not realised you gave a live link :shock: doh!)
Cathy seems to have some evidence of mould production at Crown Crystal for some of the large vases. I've not seen this before and would love to find out more. To add to my current feelings re. production of some of these vases in Europe, I would add that I have seen what I believe is catalogue evidence.
Of course it is always possible that a proportion were imported (probably the smaller ones) and then the larger versions (and there are some HUGE examples) were copied and made in Australia.
There's no doubt that this is a complex and not immediately solvable issue. The one thing that we can say with clear, "no worries", fact - the vase is called MELON RIB.