I would not go as far to suggest something an official does not see when it comes to jewelry that it is bad officiating. Not all jewelry is easily seen. It is the coach's responsibility to make sure their players are not wearing illegal equipment. That is why we ask them that stupid question before the game. We may not easily see what is on a player's ear because of their hair style, the color of the player and the color of the jewelry. I know even when looking for things, it can be difficult to always see jewelry on a player. I am not going to ever fault an official for missing something that is often very small and harder to see from a distance.
And do not get me started on hair beads.
Peace