This is a Gold Markgraf Karl Wilhelm Grunder Von Karlsruhe Commemorative Medal dated 1715 1965. I've only found one but it was a private auction in Germany, well for members only I guess. Couldn't see how much it went for, so if you have any information about this Gold medal please let me know. The medal is 9.8 grams 986 24 karat Gold, it's in a gold bazel with gold chain. Total weight is 13.8 grams. Thanks itsallngoodtime. I believe the auction house is Gunzenhausen auction hall
The medal commemorates the 250th anniversary of the city of Karlsruhe, founded in 1715. (Right, this year it has the "300 years" jubilee. ) On this page you find an auction that resulted in €120; here is one where four medals, including one like yours, fetched €500. Gunzenhausen, by the way, is a town in Bavaria. Guess you are referring to this Zwack auction which was at that place ... Christian