When I was a kid, an acquaintance jumped from the back of a stake-bed truck, ring caught on a proud nail and ripped his finger off. We once cut off a wedding ring in the shop when a motor being removed slipped and squashed the ring on. A friend reached under the hood of his car while wearing a metal banded watch. Watch made accidental contact with battery voltage resulting in instant burn. After treating with burn cream for a week, damage got bigger. Dermatologist diagnosed a photo reactive infection. He misses 4 weeks work as he had to stay out of the sun. I have met three people with out digits from chains. Two were lubing with the motor running on a stand, the third was wiping off the swingarm with a rag that got caught. I've worked around machinery all my life, and NEVER wear jewelry or watches. Just an unnecessary risk, with no reward for me.
P.S. PG&E used to show a video of people and workers damaged by jewelry causing shorts that we saw on a weekly safety meeting.