While all my kids are in their 20's now, none have peirced anything but their ears.
...............well, until my daughter came home from school break with a belly diamond.
But, she is 20 and a great kid..........never a problem with anything.
At 13 though........thats tough........
If she was wanting it because of her own expression..........thats one thing, but just because her friends are doing it...........not a good reason.
For the most part.........like clothing, hairstyles, speaking freely,...etc I have always let my kids express themselves. Remember when you were young and wanted long hair, or a tattoo or whatever...........and your parents said no?
Hey, some of my kids friends have multiple..........yes, multiple peircings.........and while I think they are a bit odd looking, they are great kids.
Hey........at least it's not a tongue piercing........