Dolph was minding his biz, eating lunch at Cracker Barrel in Fairburn, GA -- and according to a police report, a restaurant staffer interrupted his meal to say, hey ... someone just smashed the window of your Mercedes-Benz G-Wagon! Cops say this is what the thieves nabbed in the heist:

-- Richard Mille watch worth a whopping $230k

-- Patek Philippe watch worth $85k

-- 2 diamond chains worth $84k

-- 2 Cartier sunglasses worth $24,700

-- Apple MacBook, iPad, AirPods worth $3,700

-- Pirelli backpack worth $300

-- Louis Vuitton wallet worth $700

-- $2k in cash (all $100 bills)

Interestingly, cops say a Glock handgun was also stolen.

We're told police checked nearby surveillance cameras and found footage of a silver car pulling in front of the G-Wagon, and someone smashing its window. The suspect then fled in the silver car.

Dolph might be asking himself, where's comedian Russell Peters when you need him?