Thank you very much for the education. I am most appreciative for this info and will put it to use.I have collected silver flatware from all over the world. 900 is a common fineness mark for South American silver. Mexican silver will have a makers mark as well. Peruvian silver will just have the fineness mark. Bad silver from this region is mostly a form of German silver and stains greenish or blueish in my experience. Use this information as a general guide only since anyone with a jewelers catalog can get a 900 stamp.
This should arrive tomorrow and I'll have some results to show and see what we all think.
Thank you again my friend.
CHEERS!!