If it is an item that doesn't matter if it shows a little damage, you could use an acid test kit which can be purchased cheaply on ebay. If you want a non-destructive test, you may have to go to your local pawn shop/coin store/jewelry store and see if they have an instrument to test the composition of your item. I have a local coin shop that has both a handheld XRF spectrometer and a Sigma Metalytics precious metal verifier.