I have a 1906 25th anniversary medal with ribbon bracket that I got from my German immigrant grandmother. The medal celebrates the 25th anniversary of Augusta Victoria and Kaiser Wilhelm II 1881-1906. Appears as a bronze finish but not sure of that. Only saw one example in google and it was not a ribbon medal.
Germany was famous for commemoration medals like this. After all their wars except for II....Veterans Association Medals etc. It would have a particular ribbon for your jacket pocket. Grandma did good.