I have several piercings and there would be NO WAY my own daughter or even my stepdaughter (and I'm sure her mum and dad would only agree with me on this) would be allowed that at such a young age.
MAYBE 18, not even 16. Piercing is NOT something to play around with. I would also be sure to go with my daughter or SD so that I knew what kind of place it was that was doing the piercing. The reason there are botched jobs is because any old piercing "shop" thinks they are qualified to do it. Piercing should always be done in sterile conditions by a NEEDLE, not a gun. Just knowing that, my SD would definitely NOT want to get pierced!
I had my navel pierced, I took it out some time ago and it still gets infected from time to time. That's because of the position it has vs. my jeans vs. my weight gain though