Doja Cat Denies Joseph Quinn Engagement Rumors

Doja Cat's setting the record straight ... telling fans she ain't getting hitched to Joseph Quinn despite surprising fans with a ring on that finger during her performance in Las Vegas.

Here's the deal ... DC hit the iHeartRadio Music Festival stage Saturday night -- flaunting the band on her left hand and driving her fans into a frenzy of engagement rumors.

Check out the pics ... it's a big old piece of jewelry -- easy to see why some fans immediately jumped to Quinn becoming Mr. Joseph Cat.

But, Doja says this has been blown out of proportion ... saying it's a ring from David Yurman with no rocks in it -- not an engagement ring with a big ole diamond.

Doja and Joseph made headlines last month when they cuddled in London ... looking very much on a date about two years after the rapper publicly blasted JQ's "Stranger Things" costar Noah Schnapp for outing her crush to the world.

Noah later said he apologized privately and they were good ... and, ya gotta wonder if NS might've greased the wheels to make this happen -- in which case, Doja may want to send him a quick "thank you."