This is a very fine example of a slightly-vaulted pinback, privately-purchased 1914 Iron Cross 1st Class.
The paint on its obverse is 100%, with NO obvious flaws. I have seldom seen paint in as fine a shape as this. The frame’s beading is even. Its reverse sports an interesting, only slightly-swollen pin, which adds a certain je ne sais quois to the Iron Cross.
As we look under the catch, we see a “surprise,” a “KO” hallmark. KO was a firm located in Stuttgart and the Reich’s purveyor for the bulk of WW I’s issued Iron Crosses 1st Class. However, ALL of the issued Iron Crosses were flat, NOT vaulted. [In my opinion, this cross was privately-purchased by an officer. He wanted something different from the standard-issue “KO,” but may also have liked the firm’s work. Perhaps he was a native Württemberg son and it was simply convenient to buy from them].
Whatever the reason, this is a very rare Iron Cross 1st Class. It would make a fine addition to a collection that already has an issued “KO” Iron Cross 1st Class. Under any circumstances, it would greatly enhance any collection.