I was up at 5am checking the glass board. And its not like I believe an emperor sat down to dinner with this stuff 100 years ago. Dirk and Paul enabled me and now I'm obsessed. Mit freundlichen Grüßen from Poschinger gave up a clue, but offered no speculation of the manufacturer. Here's the email.
Mod: Sorry but the content of email has been deleted as it contains a specific statement that it should not be copied, disclosed or redistributed without authorisation.
A summary of its contents would be acceptable, e.g. that Poschinger say that, although the items you asked about were similar to Poschinger's production, they were not made by them. Poschinger suggested they may be of Czech manufacture.