Is it very lightweight?
I have a bottle a very similar shape, not the prettiest of things to my eyes - it's clear glass, with a background pattern of splodgy white bits, and trails of splodgey orange bits. A fairly complex thing, considering how thin the glass is. I'd say it was mould blown. It's quite big, over 12". Apart form that, I've not a clue. When Frank was here, he seemed very taken with it.
I'm quite curious, I do think they could be from the same stable.