EARRINGS ON 29 YEAR OLD MALE
If it is a private employer, certainly yes.
If one is a banker, one may be made to wear a gray flannel suit.
Employers need to project a certain image to the public, through their employees.
The only time they MAY get in trouble is the attire/hairstyle/jewelry reflects a certain "ethnic" group.
I know of an undercover cop who wore an earring. When he became a detective (suit wearer), he had to lose the earring.
Good luck to you. Is the job good? Wear the earring when you go home.