Difficult to say exactly, because of a lot of documentation that has been lost. Some of the glasses are dated for the design +/- 1900 and some 1922 but I don't know how accurate that is and when a design finally came into production. The whole series is illustrated in the 1913 catalogue but in the late 20ies they must have definitely stopped these productions as everything became more 'clean lined' so to speak. They're indestructible these glasses, great fun in different colours in summer with a (spiced up 😋) lemonade on the terrace.