David Guetta Shirtless in Miami But Hot GF Steals the Show with Diamond Ring

David Guetta showing off his abs and his hot bikini-clad girlfriend would normally be enough to focus on, but then his GF busted out a crazy diamond that's gonna get everyone talking ... ENGAGEMENT!!!

The EDM superstar and actress Jessica Ledon hit up Miami Beach Monday with their French bulldog. DG rocked his hard physique while she strutted in a blue bikini ... curves on full display.

She kept it classy too ... accessories around her neck, wrists and, of course, that ring finger.

David and Jessica haven't announced anything, but that ring's sure to set off a bunch of alarms. For what it's worth ... the ring looks like a doozy.