Thanks Sue for taking a closer look!

I think you got the technical issue perfectly right -- the golden-copper coloured areas have the foil on the surface, whereas the others have the foil covered with a very thin layer of glass, forming a sort of wavy pattern (best seen in my first pic).
What surprises me is that it is far too thick and lumpy for IoW -- the bowl looks rather delicate to me. (The shape seems totally wrong, I agree).
I had always thought IoW glass was a little bit like Mdina, which I love (wish I could find some better pieces here in Austria), but is far from thin and delicate.
Neither was the only IoW piece I ever held in my hand.
Learnt something new again...
Thanks Kane, I will try to e-mail her!
Michael