Regular Season Play:
Page 21 Equipment - Jewelry
Rule 3 Sec. 11 f All exposed jewelry such as stud earrings, piercings, non-metal bracelets, necklaces, hair beads and metal hair bands are legal. This includes medical alert bracelets and necklaces. Hoop earrings and metal bracelets are not allowed.
Other than asking a player to remove an illegal piece of jewelry there is no penalty unless the player refuses to do so, then the player will be restricted to the dugout for the remainder of the game.