hiya brian,
thanks for the additional views. you are probably right about the small mark on the ring, which is most likely a period repair that has been very neatly done. one can see the tab for the original suspension ring in there. this seems to have been a frequently worn example, and the owner wanted to avoid any recurring mishaps which could result in the loss of his cross.
again, nice item. i like these types of period-altered crosses!
p.s. it would behoove you to apply a cuetip and some water (or even better: boeshield t-9) to that core in order to remove some of the crud and prevent further oxidation