Sorry to bring this back up, I just have to finalize the issue.
The supposed nipple ring is nothing more than a white star or dot (indicated by the red lines) that is part of the design on her shirt. It is simply the effect of sharp lighting which brightens the star in the photo on the top-right. That, and perhaps a "chilly breeze".
Also, you're right, she doesn't seem to be wearing a bra.
You can clearly see in the left and bottom-right photo that there is NO 3D impression through the shirt; a telling sign a ring would undoubtably cause regardless of the angle, weather, or lighting. I assume these photos we're taken within minutes of each other judging by the location, dress, etc, so unless she removed the ring while walking down the street in broad view and the photographer managed to miss that shot...there is no nipple ring.
Thanx for clearing that one up