yes, I also drew attention to the broken place. At first, too, thought that it was a medallion, but looked at the broken place carefully and came to the conclusion that the fixture was made later than the main subject.
I'll explain why I think so, maybe a false idea.
1. The attachment point deviates from the imaginary vertical of the main subject.
2. A broken place around has a cover from another material, it is visible on the photo, as if something soldered separately.
3. The shape of the break more suggests that part of the main object is torn out as if the external object was firmly fixed on both sides (as if the pliers were ripped off).
Also, it was noted that, as a rule, medallions are damaged on the main surfaces (probably in the process of use rubs to the clothes). At the same time, more attrition on the ribs, the obverse and the reverse is practically not damaged.
Maybe I'm wrong, but I tend to think that this jewelry is from a coin.
I can take a picture of a broken place in macro mode if it is interesting.
