Hi and welcome, Anik!
I think you´re right about the Wiedmann attribution, but as far as I know, they were designed during
his work with Gralglashütte Fischer & Seyfang. Unfortunately there´s close to zero information available,
but a visit to the Gralglas Museum in Dürnau is on my to-do-list.
BTW got one of those, too. I´ll post a picture this evening, as I´m @work right now.
Cheers,
Dirk