EXCLUSIVETyga is rolling around town with some sick jewelry -- a diamond watch and chain worth more than $91,000 -- but problem is the bling ain't his ... at least according to a lawsuit filed by a famous Beverly Hills jeweler.
In the suit, Jason of Beverly Hills claims the rapper agreed to drop $28,275 for the jeweler's diamond pantheon watch back in August, 2012.
JBH also claims Tyga -- real name Michael Stevenson -- borrowed a $63,000 diamond Cuban link chain in December, 2012 -- but never returned the piece.
Now JBH is suing for the cost of both pieces, plus late fees ... which just about doubles Tyga's tab to a whopping $185,306.50.
We called Tyga's peeps for comment ... but haven't heard back.
RICH FUN FACTS: Jason of Bev Hills has also iced up Justin Bieber, Mariah Carey, Diddy, Beyonce, and LeBron James. If nothing else, Tyga has good taste.