Some charms are little inside jokes between people who get each other, and a friend charm is exactly that. Give one to the person who's been there through everything, keep one yourself, and let your Italian charm bracelet carry a bit of that history around with you.
Colour that lasts, wear that shrugs off water and daily life, and a piece you can move around whenever you want. Nothing fussy.
Best as a matching set: one for you, one for your other half of the friendship.