Hi, I do not have much to add, except that the vase with a mark mentioned by flying free from Ruby Lane definitely reads
made in
Czecho
Slovakia
Like other "cellophane" type pieces, these are generally regarded as Czech, albeit without a lot of documentary evidence. I happen to agree and several factories in the area of Bohemia that are not well documented produced good quality glass such as this. Agreeing with a comment by rocco earlier, I suggest CMS Krasno, a Moravian Czech factory, which was not a small factory, which made ranges involving techniques that could have easily produced most of these items, including the item in this thread, also finishing pieces with a similar base finish technique. I know CMS Reich produced some items that were only labelled with a paper and foil label, not acid marked, which many CMS Reich pieces also were known to have. The location of the pattern books of CMS Reich Krasno are not known to me. So, this piece is still slightly mysterious!
It would be interesting to know, re. WMF, if their unika pieces were unsigned.
Robert (bOBA)