Hilary Duff Is Back From Vacay, Debuts "Blue Mermaid" Hair Color

Hilary Duff is feeling blue! For her hair, that is: The star took to Instagram on March 18 with a photo of her dip-dyed teal locks.
The change follows a sunny beachside retreat that Hil took with 23-month-old son Luca and a few of her closest girlfriends (the hot mama even shared a sexy bikini shot, along with a message encouraging other mothers to be proud of their post-baby bodies).