A man tried on a pricey watch at a Midtown luxury store — then ran out the door with it, police said.

The suspect, captured on surveillance camera, entered the Tourneau Watch Store on 57th Street near Madison Avenue about 2:50 p.m. yesterday, cops said.

He asked to see Cartier’s Ballon Bleu model, which is valued at $8,100, and tried it on, according to authorities. The watch has a sapphire crystal, and its strap is made of pink gold and steel.

The sticky-fingered shopper then took off — running east on 56th Street towards Park Avenue.

Police are asking anyone with information about the heist to call Crime Stoppers’ hotline at 1.800.577.TIPS, or to send tips via the Crime Stoppers’ Web site.