Odd uniforms I can live with.
Jewelry, undershirts, headbands, and wristbands: By the book.
If you ignore jewelry and it somehow, in a crazy situation, causes some type of crazy, odd, injury, there may be legal ramifications.
I've posted this before, but it's worth another read: If you think that the "Fashion Police" rules can't be enforced consistently, then guess again. Undershirt, headband, wrist bands, and jewelry rules are strictly enforced in the Catholic middle school league that I work. If we, as officials, don't enforce these rules, we don't get paid by our assigner. All officials know this, as do all coaches. After a few reminders the first week of the season, we no longer have any problems with these "Fashion Police" rules. No, "The officials last week let him wear his lucky stars and stripes headband". And some of these kids are in second, or third grade, coached by volunteer parents. If they "get" the rule, then high school players, coached by paid coaches, can "get" the rule.