Three slick thieves smashed and grabbed $2 million in bling from a Four Seasons display case just feet from the Midtown hotel’s front desk yesterday — and made a clean getaway, The Post has learned.

The crooks snatched three watches, a necklace, earrings, rings, cuff links and pendants from the Jacob & Co. case at around 2 a.m. and fled in a waiting car on East 57th Street, sources said.

“It was quick. They hit us, smash and grab, gone,” a security worker said. “We certainly didn’t expect to get hit there.”

With an accomplice waiting in the car, the other two men waltzed into the famed hotel and ascended two flights of stairs to get to the ornate lobby surrounded by a dozen windowed cases from an assortment of high-end retailers.

They struck up a conversation with a hotel staffer about the Jacob & Co. case while concealing a sledgehammer, sources said.

When the coast was clear, one of the thugs smashed the glass and they scooped out the jewels. The pair then strolled untouched out the front door.

Their escape was assisted by a shocking amount of faulty surveillance cameras in the Four Seasons lobby.

“Can you believe that most of the cameras in the hotel are not functional?” a source said.

The embarrassing breach, sources say, has hotel security team members fearing the worst.

“Trust me, someone in security is worried about his job,” one source said.

Detectives were poring over video footage taken from the Avakian Boutique jewelry shop steps away from the concierge desk.

E-mails and voice messages left with the hotel and its staff were not immediately returned.

“The [hotel] is trying to keep it hush-hush,” a source said.

Hours after the heist, the hotel’s security detail was spare and staffers stumped.

“The glass broke,” said one worker in the lobby — where the panel that once held the Jacob & Co. jewelry was boarded up with a black fiber wooden block.

“I can’t tell you nothing about nothing,” said a man named Neil, who identified himself as hotel security.

“I haven’t heard of any incidents,” the manager said, before suggesting the wares were all housed by Jacob & Co.’s store across the street. “I’m not aware of anything happening.”

The security snafu was a surprise to one law-enforcement source.

“In the past, their security has been good,” the source said.

A guest of the Four Seasons was taken aback after learning about the theft.

“I’m incredulous,” said Allan Plank, who was in town on business.

Jacob & Co. is owned by “Jacob the Jeweler” Arabov, 47, a jeweler to the stars who is known in rap circles as the “King of Bling.”

He has his share of trouble with the IRS — and served more than two years behind bars in 2008 for misleading feds probing a money-laundering operation by Detroit’s Black Mafia gang.

Nobody was home yesterday at Arabov’s two-story brick house in Forest Hills, Queens, which is currently under a tax lien.

A neighbor said he was out of the country.