"...tell him you're concerned about "world conditions". ..." LOL!! Good one, XYZ!!
Might actually work, too...
I'm a little confused... And would like some further background on the situation...
Who has "seniority" - though that doesn't apply very often any more??? Were you employed there when he was hired, or vice-versa??
Does he hold a position roughly equivalent to yours, of "less" importance than yours, or of "greater" importance???
Some people have mentioned a potential "romantic" issue; are you older than him - or is he older than you - by enough years to basically rule out a "romantic" interest...???
Having asked those questions, I would say that he generally "sounds" like a Jehovah's Witness, but he could have all those hang-ups you mentioned and NOT be a JW. He could be a fundamentalist Christian; his fear/unease/revulsion displayed by his reaction to your jewelry would be common to ANY fundamentalist Christian, not just JWs...
I would advise CAUTION, CAUTION, CAUTION... I would also second Nelly 136, who said to keep things professional, professional, professional... Could keep you from ending up in some sort of disciplinary action, if he decides to cause problems for you...
Hope this helps...
Zid