The salesman was in town from New York City and was traveling between stores in Seattle and those on the Eastside. He stopped to get a bite to eat and use the bathroom, but when he came back out those precious goods were gone.
Someone broke into the back seat of his car and took two suitcases filled with that half a million dollars in diamonds and jewelry.
Surveillance video shows a van that followed the car into the Mercer Island parking lot. It takes less than a minute for someone to break in, steal the goods, and take off.
Police wonder if someone was following the salesman who was carrying the diamonds.
"These jewelry gangs will set themselves up adjacent to jewelry districts or jewelry stores and be on the lookout for these couriers," said Det. Peter Erickson with Mercer Island Police.
Mercer Island jeweler Chris Francisco says he's sometimes visited by jewelry salesmen, who have a tough job traveling from the Diamond District in New York to local stores to sell their goods.
"What I know is they're traveling, they've got at least $2-3 million dollars, not just half a million," Francisco said. "They can't leave it in the hotel. They usually would leave it in the car."
The only leads police have are the surveillance videos of the suspect's car and generic photos of the glittery goods that were taken.
Detectives think these bright and shiny gems might turn up on the black market.
So why did the dealer leave the gems in the car?
"Pardon the pun: That's going to be the million dollar question," Erickson said. "Why he didn't take his jewelry with him?"
The New York-based diamond dealer who owns the jewelry says he is insured but insurance will not cover this because the jewelry was left unattended.
The owner told us: "We always tell them not to leave the bag unattended. We told him 15, 20 times at least in the past few months."