Hailey Bieberis very quick to return a favor, because just days after she turned 23 ... the missus got her hubby something arguably nicer than the birthday gift he gave her.
Justin's showing off this new iced-out necklace he just got from L.A. jeweler Jadelle Beverly Hills. Even in the dimly lit pic, you can see just how damn blingy the chain is -- and we've learned Hailey actually picked it up for her groom.
Our sources say Hailey reached out to Jadelle -- a favorite shopping spot for the couple -- and surprised Justin with it in Miami, where they're currently on a working vacay. As you can see, Hailey's the one working..
Happy husband, happy wife ... and REALLY happy jeweler!!!