I need some advise from you wise folk.

I made a piece of silver jewellery the other day textured it slightly with my rolling mill, soldered a cup, set my stone and polished it up a treat.. looked lovely and I was very happy with my new creation. Next day I noticed that the piece had tarnished slightly but there was a kinda discolouration around the cup that was lovely and shiny compared to the rest of the piece.. I'm now gutted because I can't sell this beautiful piece but what could have caused this I have never had this issue before..

Any advice would be much appreciated.