Rummers from the table service "Wilhelm"; Rheinische Glashütten AG, Cologne Ehrenfeld, circa 1888. Light green glass, stem with enclosed spiral hollow threads; offset knop, height 19.5 cm.
Literature: W. Schäfke, Ehrenfeld glass from the Historical period, Cologne 1979, 180, no. 435
Now that is pretty well researched. I doubt if you'll find a designer (they only appeared by name after the turn of the century) but the year is clear and so is the reference.