Silver ring..finger green?

I got a silver ring when I was on a mission trip in Haiti over my spring break, I wear it everyday, and now where it lays on my finger is greenish. Please don't tell me it's not real, because I know it is, I even met the guy who made my ring and they are not technologically advanced enough to make a copper ring and cover it with silver. It's an imprinted ring, with indentations directly into a plain silver band. Please tell me what to do because I love this ring and the memories it holds and don't want it to keep doing this. If there is anything I can do besides put clear nail polish on the inside would be awesome, because I don't really want to do anythign like that.