Tiffany & Co. held its Blue Book Ball in NYC last evening, and celebrities paid homage to the brand's iconic boxes in shades of beautiful blue. Kate Hudson chose a gorgeous Reem Acra gown in a strikingly similar Tiffany-blue hue. Both Jessica Biel and Michelle Williams opted for deeper navy hues in Elie Saab and Katie Ermilio, respectively, and Gwyneth Paltrow took time off her Iron Man 3 duties to attend the ball in a steel-blue Ralph Lauren gown. Watch on for all our coverage of the glamorous night! On Allison McNamara: Club Monaco top, Bebe shorts, H&M jacket, Vita Fede bracelets.