Halle Berry -- Rips CURLS on the Beach

Halle Berry went au naturel at the beach this weekend -- not in a topless way -- but in a badass 70s hairstyle kinda way.

Halle and fiance Olivier Martinez took a romantic stroll ... and flashed her massive emerald engagement rock in Malibu.

Halle's been very vocal about her desire to move to Olivier's native France ... partially to escape the paparazzi in Los Angeles -- but she looked pretty chill this weekend, sporting her curly 'do.