Sharon Stone reportedly celebrated her 60th birthday as a bride-to-be after sporting a new diamond on her left ring finger.

The Basic Instinct star marked her age milestone on Saturday, two days after she was spotted hitting the beach in Miami, Florida with her boyfriend Angelo Boffa.

Sharon was dressed in a colorful bikini top, drawstring pants, and sandals as she strolled beside the shirtless Italian businessman, who donned a pair of denim shorts and boat shoes for the outing.

However, the couple turned heads as Sharon was also wearing an extra accessory on her left hand – what appeared to be an engagement ring featuring an emerald cut diamond.

She only made her relationship with Boffa public in January, when they stepped out in New York City to celebrate the release of her murder mystery series Mosaic with director Steven Soderbergh.

Representatives for the actress, who is mother to adopted boys Roan, 17, Laird, 12, and Quinn, 11, have yet to comment on the speculation.

If the engagement news is true, it will be Sharon's third marriage. She was previously wed to TV producer Michael Greenburg from 1984 to 1990, and married newspaper editor Phil Bronstein in 1998. They separated in 2003.

Stone also enjoyed engagements to producer William J. MacDonald in 1993, and to director Bob Wagner in 1994.

Shortly before finding love with Boffa, Sharon admitted she had given up on dating in favour of focusing on raising her kids, particularly as most suitors are turned off by the idea of romancing a single mother-of-three.

"I have so much love with my kids," she explained to news show Entertainment Tonight in May, 2017. "I have three little kids, and that's not particularly, in this town and environment, there's not a lot of men that think, 'Gee, I'd like to date her and be the baby daddy of three little kids'. So, it kind of took me out of the dating sphere."