Outside.
Put it inside and it looks like you have a problem with your ankle.
Definitely outside. But I wouldn’t really wear one with stockings. Then again, I usually go bare. I hate stockings.
Ankles… mmmmmmmm
Ankle bracelets… oooohhhhh, mmmmmmm
Ankle tattoos… woooooh, oooooohhhhh, mmmmmmm
Ankle ribbons… ngh! Ugh! Oh my… 
Ever since I was about nine years old, I’ve made ankle bracelets, and I don’t think I have ever worn one inside of hose or tights.
Besides the fact that I rarely wear hose, it bugs the crap out of me to see a wrinkly little flattened down chain.
…so many Dopers were on house arrest, having to wear that bracelet…