CALISTA FLOCKHART celebrated her 50th birthday in true Hollywood style – with an impressive new face!

The social scene in Los Angeles hadn’t seen much of the actress after she marked the big 5-Oh-No! this past Nov. 11.

Then she showed up with hubby Harrison Ford at the Golden Globe Awards on Jan. 11 – and experts told The National ENQUIRER that it appears Calista owes her stunning new look to spectacular plastic surgery!

“Calista has had some beautiful work done by a real master. I see the hand of a friend of mine in all this!” raved Dr. Lyle Back, who hasn’t treated Calista, but was one of three plastic surgeons offering a professional opinion to The ENQUIRER.

“[Her] nasolabial folds are lessened; bands under the jaw are less. Her cheekbones are more prominent, and the lower face is tighter,” said facial plastic surgeon Dr. David Alessi.

“In my opinion, it is probable that she had … a limited lower facelift.” Dr. Yoel Shahar, a cosmetic surgeon who also hasn’t treated Calista, added: “She probably had Botox done, since the lateral eyebrow is higher and there are no visible, angry lines.”

While a rep for Calista said talk of a nip and tuck was “absolutely not true,” her new look has also prompted talk in Calista’s swanky L.A. suburb!

“Calista was out of sight for a couple of months – but it’s common for men and women in Brentwood to just fall off the grid for a while when they go in for plastic surgery,” one local insider divulged.

“Then, voilà! Calista’s back as if nothing has happened – but something clearly had happened. “Her face was completely immobile!”