Since your jpg indicates "Iron Cross" I guess that much you already know. This particular piece is a 2nd class award and the link below will give you more specifics.
http://www.wehrmacht-awards.com/iron...roncross_2.htm
Since there were 2 million plus awardings of the 2nd class iron cross and rarely were German awards attributed to individuals (unlike their English counterparts) I would consider this virtually impossible unless you know the path prior to your taking posession of this piece.
The ring stamp relates to the manufacturer, I believe the link I sent deals with this in part as well.