My wife and I both have single nipple piercings and wear horseshoe style rings. Her's shows through on most shirts, as she wears shear bras. Kinda looks like 3 nipples with the ball ends showing through
She get's quite a few stares
Plus her nipple (and mine) are constantly at attention. But you wouldn't have anything to worry about if you wear a padded bra. I've never had anyone notice mine unless it was at a dance and she felt it while feeling my chest
Brett