OLIVIA HARRIS / Reuters 1 / 13
OLIVIA HARRIS / Reuters 1 / 13

Mommy's night out!

Fresh from her family vacation with Prince George in Mustique, Duchess Kate swapped her favorite navy jeans for a navy dress for the Portrait Gala 2014 at the National Portrait Gallery in London on Feb. 11.

PHOTOS: Kate's post-baby style

The elegant blue silk tulle Jenny Packham gown features a black velvet belt to highlight her tiny waist and gathered material on the sweetheart-necklined bodice. Kate debuted the dress in October 2013 at the 100 Women in Hedge Funds Benefit Gala.

The duchess, 32, complemented the simple-yet-stunning gown with bling fit for the queen -- literally. The "Nizam of Hyderabad" necklace was a wedding gift to Queen Elizabeth II and loaned to Kate for the event. The 1930s Cartier necklace consists of 38 diamonds on a chain and a center pendant with 13 emerald-cut diamonds.

PHOTOS: Kate's body evolution

Kate wore her signature loose-waves hairstyle and kept her makeup simple and sophisticated with a subtle smoky eye and pink lips.

PHOTOS: Prince George's baby album

While Prince William didn't attend the Portrait Gala, the event marks Kate's first royal outing of 2014.

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