My co-worker just got fired...?

Take the watch to HR!! Hell, give her a call and let her know that she can pick it up there because believe me, if you were to bring it to her, she'll talk your ear off about how she was the victim and it will undoubtedly put you in an awkward position and not only that, why would you even consider doing it?! You didn't really dig on her, so why go out of your way?