Boosie Badazz hates Mondays, like most of us -- actually, probably more -- because someone broke into his ride, and made off with some pricey rings and a $50,000 necklace!

While the rapper was grabbing a bite to eat at a Pappadeaux Seafood Kitchen outside Atlanta, the perps smashed the rear passenger side window of his Bentley SUV ... according to police.

A man named Brian Wilcott reported the break-in, saying he saw a younger-looking black male by the car reaching into it. Wilcott -- better known as rapper B-Will -- works with Boosie and told cops he gave chase, but a suspect jumped into a waiting car and fled.

According to the police report ... B-Will says 3 pieces of his jewelry were stolen -- a "super bowl style" diamond ring valued at $10k, a large rose gold one with the diamond letters "BOSSMAN" valued at $10k, and a rose gold Cuban link chain with diamonds valued at $50k.

Although B-Will told cops the jewelry is his, it's interesting ... because we know Boosie has a "BOSSMAN" ring, and the rapper ranted on social media about it getting jacked, and even threatened the suspects.

Cops say they reviewed surveillance footage from the restaurant, which shows 2 black males dressed in black messing with Boosie's Bentley ... which set off the alarm. The report says the 2 men drove away, but quickly returned to the vehicle, then sped off for good ... at which point B-Will is seen running after them.

We're told no arrests have been made so far.