This is a subject that I have deep interest in; case stamps that are rare, uncommon, strange, seldom seen, or anomaly's. So why not start a thread? Since these stamps are often on the inside caseback, I suggest adding a shot of the full case, and mentioning the calibre if it's not clear, for context.
Interesting one "GOLD FLD"
Very uncommon "18k" in "eye" . Cal 127.