"Baby do you like it? I just want to get you wat you Like ! I just wanna Mk you smile :) #takeDat. !," he wrote, along with the picture of the enormous rock.
Cassie was also photographed wearing the ring on her ring finger, but that doesn't mean they'll be taking a trip down the aisle anytime soon.
Diddy's rep confirmed to E! News that they are NOT engaged, despite reports and speculation to the contrary.
So, it sounds like this was just a "just because" ring.
The music mogul and his ladylove have reportedly been dating since 2007.