She debuted her Art Deco-style diamond engagement ring at Venice Film Festival this week.

But Scarlett Johansson was the ultimate professional at the Toronto Film convention as she kept her giant rock under wraps while posing with Jessica Chastain.

The 28-year-old starlet slipped her curvaceous figure a checked figure hugging dress while Jessica, 36, looked excellent in 60s’ inspired white lace.

Beauties: Actresses Jessica Chastain and actress Scarlett Johansson looked demure at the Variety Studio at Holt Renfrew during the 2103 Toronto International Film Festival on Monday

The Match Point actress put her blonde locks into an elegant ’40s style quiff and donned a chunky pair of on-trend patent brogues.

The four-time Golden Globe nominee began dating Romain Dauriac last November after reportedly meeting through tattoo artist Fuzi Uvtpk.

Dauriac – now a creative agency manager – was the former editor of French magazine Clark, which specialized in underground urban art.

Johansson first opened up about her man in the May edition of Marie Claire.

‘My boyfriend and I were saying, “We were the best dancers in the whole world last night!”‘ Scarlett said of one of their shared passions.

Chic: Scarlett looked flawless with just a slick of pale lipstick

Impeccable: The two actresses looked wonderful in their chic dresses

‘[We were] completely delusional. I’m sure we were absolutely, like, ridiculous together.’

And if the journalist plans on keeping the gorgeous Tony winner around, he can’t become jealous.

‘I don’t mind an occasional check-in, but when somebody is passive-aggressively jealous, it’s really unattractive because it shows a sort of insecurity that is…Oh, controlling behavior is awful,’ Scarlett revealed.

‘Nobody’s going to say they love that.’

After the Lost in Translation star split with husband Ryan Reynolds in 2010, the hunky leading man wed Blake Lively a year ago.

Attractive couple: Johansson debuted her Art Deco-style diamond engagement ring alongside her tuxedoed beau at Venice Film Festival this week

Johansson has previously romanced fun. guitarist Jack Antonoff, Jared Leto, Sean Penn, and advertising creative director Nate Naylor.

The Avengers actress can currently be seen as a seductive alien in Jonathan Glazer’s flick Under The Skin.

She’ll next appear in Joseph Gordon-Levitt’s directorial debut Don Jon – due out September 27 – about a porn-addicted ladies man who learns to be less selfish.

Scarlett also told Marie Claire that she plans to adapt and direct Truman Capote’s Summer Crossing next year.

Indie starlet: The Avengers actress can currently be seen as a seductive alien in Jonathan Glazer’s flick Under The Skin

Coming September 27! She’ll next appear in Joseph Gordon-Levitt’s directorial debut Don Jon about a porn-addicted ladies man who learns to be less selfish