The incident happened at about 10 p.m. Thursday as the victim waited for a gate to open to his complex located near Robinson Drive and Clifford Court.
Police said a man on a motorcycle and one or more suspects who exited a white truck threatened the victim with a pipe.
The jeweler, who owns a store in Los Angeles, was returning home from a private jewelry show in Orange County when he was robbed.
The victim's identity was not immediately revealed.
If you have any information regarding this heist, you're urged to contact Tustin detectives at (714) 573-3250.