Tiffany & Co. Gift?

For my 15th birthday my parents are getting me some nice jewlery from Tiffany & Co.
I can’t decide what i want. I do like the heart tag toggle necklace (and bracelet), but i’m afraid as i get older, i won’t wear it because it’s too youthful, and i want a timeless piece.
any suggestions on what i should get?
nothing too too much, my parents have to keep telling me its a birthday, not christmas, so no $20,000 platinium/diamond necklaces:(
Thanks guys!!