thanks Anne - I don't recall whether this 'trademark' was on the one tray I had - too long ago.
I've filched this from elsewhere ................................ "Heinrich Hoffman lived from 1875-1939. At the turn of the 20th century, he had an artist's studio in Paris, w he made glass molds. The molds were then sent to Bohemia, where his wife, Josephine, was in charge of making the glass. Hoffman's trademark was a small, open-winged butterfly that is frequently (but not always) on his glass."
Perhaps this was what Lustrousstone had in mind - but anyway it's useful to have an explanation, even though it appears not to be a hard and fast rule. I've looked quickly through the Newhall 'Sklo Union' book, but couldn't see a close match, but would be surprised if there wasn't something similar on the CD catalogues, even though it seems the edge/rim is cut?
So, we'll go with the suggestion of post-war Czech for tea bags (philistines)

/herbs/pins/butter curls/cocktail ashtrays