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Everything points to Alsace/Belgium for me too: the spatter ground, and the green fronds either side (the latter pointing more towards Alsace, perhaps). If it were antique French I would expect it to be heavy lead crystal, probably with a polished concave base. I have only seen signed sulphides in French weights.
As for age, my guess is 1880 - 1920. It is very difficult to suggest a maker - there were many, many glass factories in Belgium and Alsace who made spatter ground weights.
Alan