When I wore green in the J, you didn't wear anything that flashed, jingled, sparkled, stood out, or that could give away your position - or wear anything that could get caught on projections, when jumping off vehicles/APC's/tanks.
Numerous blokes lost fingers when jumping down off stakeside trucks, and rings on those fingers caught on protruding bolt shanks.
And anyone who has stuck a hand/arm close to anything full of electrickery with exposed bits, knows all about, how metal bits on digits and arms and legs can arc themselves to said components full of electrickery.
Starter cables are a classic - seen some particularly nasty deep burns when about 500 or 600 amps from a battery welded the jewellery to the cable terminals.
I've never worn a piece of jewellery in my life and not silly enough to get a single tatt, either. I can develop enough medical problems without the assistance of quantities of dodgy ink and dies being permanently ingrained in my largest body organ.
I am carrying around a chunk of steel shrapnel lodged against a lung wall, so that's enough metal, in or on, the body for me.
It's a whole new world today, though - one used to be able to ID the difference between a girl and boy, as to which one was wearing the jewellery. Nowadays the bloke is likely to be wearing more jewellery than the girl.