Lily Collins Wore a Plunging Tuxedo Jacket with No Pants

Pants were seemingly optional at Cartier's rooftop dinner and private viewing of the brand's Clash [Un]limited capsule collection in Los Angeles on Tuesday night. With the right jacket, that is — and brand ambassador Lily Collins got the memo.

For the event, Collins, who was joined by her fiancé Charlie McDowell, wore an elongated blazer as a dress with nothing underneath. The couture jacket by Dutch designer Ronald van der Kemp featured a peplum waist, exaggerated shoulders, and a dramatic train that hit the floor. The actress accessorized with a black clutch and a pair of matching Mary Jane pumps.

Beauty-wise, Lily kept it classic with a red lip and a retro updo.

RELATED: Lily Collins Wore a Chaotic Bucket Hat and Dress Combo on the Emily in Paris Set

Last week, it was announced that the star of Emily in Paris was the new of Cartier's Clash [Un]limited collection. "When it came to expressing the duality of the Clash [Un]limited jewelry, Lily Collins was the obvious choice," said the brand's international marketing and communications director, Arnaud Carrez. "Unique and committed, Lily Collins embodies a new generation of artists who dare to reveal their different sides, sometimes classic and elegant, sometimes creative, sometimes even extravagant. In summary, people who do not limit themselves."