2 / 5

Allison Williams, Katy Perry

Katy Perry went vampy for the evening in a body-hugging navy Naeem Khan gown and 45-carat blue sapphire and diamond earrings by Lorraine Schwartz, and chatted up fellow guest Allison Williams, who appears on TV’s “Girls.” (11/27/12)

Stars Glisten at the 2012 Snowflake Ball

Selena Gomez, Katy Perry, and Uma Thurman kick off the holiday season – and help a good cause – at the UNICEF black-tie gala.