Katy Perry Engagement party dress jenny packham

Photos: Jenny Packham cocktail dress on the runway (left) and on Katy Perry (right). Photos: Courtesy of Jenny Packham | X17Online

Saucy singer Katy Perry celebrated her engagement to British actor Russell Brand at Il Cielo restaurant in Beverly Hills, Calif. on Wednesday night.

The pair enjoyed dinner with about 50 friends and family members, according to X17online.

For the happy occasion, Perry wore a black chiffon tiered cocktail dress from designer Jenny Packham's Spring 2010 collection.

Perry was spotted leaving the restaurant on Jan. 13 in much more casual attire -- an oversized T-shirt, capri gym pants and sneakers.

Perhaps scouting the location and making some last-minute party menu additions?

Perry and Brand got engaged in Thailand on New Year's Eve, after which Perry promptly proclaimed her love for Brand on Twitter and began sporting this engagement ring.

And read about this newly engaged model's ring.