The thing is, all finishes are different. The last ones have a black enamel rim, others cut and polished, others rough. The colours range from clear, via various sorts of green, to amethyst and cobalt blue.
Both Welz and Rückl do not seem to have made glass shapes - just lots of colour. Not seen any iridescent finish on blown glass from them.
Doyen I do not believe because they tend to have a wavy rim.
Here's a few more.