Annoying how my brain seems to forget things...

While researching / Googling, I noticed that the decor found on my ashtray is often referred to as 'argentum' by other sellers, and that pieces attributed to Wiedmann (both WMF and Gralglas) show up in search results.
Then I remembered this thread with a vase and bowl which was initially believed to be Wiedmann designs for Gralglas:
https://www.glassmessages.com/index.php/topic,49201.0.htmlMichael's pieces have exactly the same decor as my ashtray.
In that thread, I wrote that the pieces are Polish (Huta Julia), designed by Aleksander Puchała. I went back into my old photographs and found a photo with a vase like Michael's, and with a partial Huta Julia label. (I've included it here, but it's been cropped from a larger photo which isn't mine, so it's very small... moderators, I understand if you delete it.)
Since the decor is exactly the same as in my ashtray, I think it's proof that it is, indeed, Polish.
Anik
P.S. Ivo, thank you again for helping to get my brain juices flowing. Much appreciated!