It does look similar to shape XA (just spent 20mins looking at your great piccies!)
I will try to describe how i think its put together.
I think its hand blown, not mould, its not completely round at the top, theres lots of
striations(is that right?) rings in the glass, also bubbles and some ash particles,
looking side on , the base appears clear,(about 1cm deep, so maybe applied although
cannot see or feel join) and the pontil is polished about 2 1/4" wide, almost the whole of the base.
Im hoping you may be leaning towards Monart :huh: :huh:
That would be nice, its certainly well made
Look forward to your opinion with anticipation