On Saturday, the blissed-out couple had a very romantic night out at the celeb-fave spot Chateau Marmont in Hollywood, where Aniston, 43, and her Wanderlust costar, 41, hung out at a private, tucked-away table in the garden area, an onlooker told Us Weekly.
Casually clad in black top, blazer, jeans and black ankle boots, Aniston wore minimal makeup, with her hair down; the most eye-catching part of her ensemble was her enormous engagement ring. Although Theroux proposed back in August, Aniston didn't publicly debut the rock until last Saturday, Oct. 6 in Santa Fe, New Mexico.
A glowing Aniston gazed lovingly at her hunk (wearing jeans, white t-shirt, jeans and leather bomber jacket) as they chatted during their meal, with Theroux reaching out to rub her hand. Actor-screenwriter Theroux rubbed the small of her back as she rose from the table; as they slowly ambled out of the hotspot, the husband and wife-to-be held hands.
Aniston has been shooting We're the Millers in North Carolina for the past couple months.
Of the star's huge new bling? "It looks like a radiant cut center diamond, approximately 8 carats," jewelry designer Peter Meksian from Michael M. told Us Weekly, estimated that the bauble cost an approximate $500,000.
Sign up now for the Us Weekly newsletter to get breaking celebrity news, hot pics and more delivered straight to your inbox!