Are you near to a University? They have spectroscopy machines that will give you an alloy readout. Also, there are some companies that make XRF hand held devices that will also give it to you - sometimes jewelers have them (I've been trying to find them around here in MD, USA without success). I have one of each type I think but not sure where they are.
Allegedly, and according to Groom, the Sterling examples have sharper margins to the E's as was stated just above which is what mine had by recall. I'll see if I can locate these after work today. If you PM me email I will send them to you.
As a footnote, I have many times seen written that a finer (higher percentage) silver coin will have a "duller" ring when rapped than a more base example. I personally have found that NOT to be the case. A better silver piece when dropped has a much clearer ring, almost as a bell, than the dull thud of a lower fineness or base example. That would demonstrate a higher pitch.