What gift should I get my best friend?

My friend is turning 16 in a couple of weeks and I'm hopeless with gifts. This is possibly our last year together as we're splitting up and going to different colleges so I wanted to make it something special. I can't do a photo montage as she already got one from before and I'm all out of ideas on how to make it special/personal. She has a bubbly personality and is kinda girly too, so I was thinking like a locket or something? Or is that not the right type of present.