Jeffingtons one of the real problems with Japanese glass is figuring out who were maker and who wholesaled like for example Mikasa or Kamei. I run a FB group on 'Japanese Glass' and a couple of members arre serious collectors. My interest in learning moreis the realisation that a lot of Austtralian "Murano" clear cased glass was in fact Japanese. I too love better quality if nulticolour. Here is a labelled large vase by Iwatsu - who made several well known lines including Sanyu and Hineri - as far as we have been able to ascertain so far. I have als included a favourite lamp base (?) that is identifired as Iwatsu by the medallion attached to the front.
Ross