Silver / Silverplate Antique Tea Ball Diffuser

I tend to drink coffee all day long, but a lovely antique tea ball like this one makes a very strong argument for switching to afternoon tea. So civilized--and liberating in being able to mix one's own loose teas. I have found an exact match of this one described as sterling, but I can't find a mark anywhere so have to assume it is silver plate. I did a quick pass on it with silver polish and it shined up easily, and it should shine up some more. The lid opens easily and snaps tightly closed. 

It's been well used, with a few noticeable spots, light scratching, and a few small dings, as pictured. 1 1/2" in diameter; the chain with loop is 4 3/4" long.