Is it silver?

I was at an outdoor show this weekend and something interesting happened.  

On the last day of the show, a well-dressed woman came into my booth with her daughter and a friend. After looking at my jewelry, she tried on one of my sterling silver necklaces. With the necklace on, she asked me if the necklace was sterling silver.  I assured her that it was and she told me something that had happened the year before at this same festival. She bought a piece of silver jewelry that was supposed to be sterling silver.  After a period of time of wearing and enjoying the jewelry, she noticed that the silver seemed to be "wearing off".  Thinking that the jewelry was beginning to tarnish, she proceed to try to clean it using the typical methods (polishing cloth and, I assume, silver "dip").  When that was unsuccessful, she took the piece to a local jeweler who informed her that, not only was the piece not sterling, but that she had "ruined" the piece trying to clean it.  

I proceeded to assure her that the necklace that she was trying on was sterling silver and that I was aware that sterling "fill" or "plate" became popular a few years back when sterling silver prices became prohibitive.  She left my booth without purchasing the necklace.  

After she left I continued to think about what I could have said to convince her that the necklace was indeed sterling silver. Having done a little research, I have learned that there really is no reliable test for sterling silver as opposed to silver plated or silver filled.  My piece was not stamped ".925" but that would not prove anything since I made the piece and could stamp it with whatever I wanted.  

I am still left wondering what I could have said (or not said) that would have helped this potential customer trust me - that's what it comes down to, after all.  And what about the jeweler who pronounced the piece "not sterling"?  What was his interest in this?  Clearly, he may have been interested in securing his position as the only "trusted" professional, thereby insuring that she would buy from him rather than "street vendors" such as myself or my fellow artists.  

What a shame.  Trust is everything in this business. 

---