Brian Hassine, the owner of Nuggets & Carats Fine Jewelry & Art, said a gunman, wearing no disguise, held him and his three employees hostage while two other men smashed his showcases.
Police said the alleged thieves stole several hundred thousand dollars in jewelry, according to CBS Los Angeles.
"All our rings and our watches are gone," said Hassine.
Hassine, who said the gunman threatened to kill everyone, told the station he watched the heist unfold from his security cameras in the back room of the store.
"I kept thinking he's going to have to kill us. We could identify this guy," said Hassine.
Sheriff's deputies said the suspects fled in a white sports utility vehicle, reported stolen out of Lakewood, then abandoned it and escaped in another car. They reportedly left rings behind on the floor of the SUV.
The suspects were described as black men in their early 20s. The gunman was 5 feet 11 inches tall, weighing more than 200 pounds, and had short hair.
Store owner Hassine is known for designing the wedding ring of Tamra Barney, who stars on Bravo's "The Real Housewives of Orange County."