And how is that different from around his necK?
My guess? Because it’s not as visible.
Re: “And how is that different from around his necK?”
My best guess at this time is that it’s not about the symbol on the necklace, it’s the fact that the necklace is a dangling item that might get caught in a door / machinery / a passenger’s coat (remember, we are talking about a potentially crowded tram) / whatever. The other options — ring, earring, and even headscarf — don’t dangle, and perhaps are less likely to get caught on something.
Yeah, I’m not completely satisfied with that explanation either. But it does make at least a little bit of sense.
Many professions do not allow necklaces. I was in nursing a while, we were never allowed to wear necklaces or long earrings for safety. My husband was a printer for a while, he never wore a ring.