Sexy! Kate Middleton Wears Low-Cut, Lace-Back Gown and Braided Updo

Catherine Middleton and HRH Prince William pictured arriving at the Royal Albert Hall on May 11, 2012. Credit: Splash News Online

It's a statement-making day in royal fashion history: Kate Middleton has stepped outside of her style and beauty comfort zone!

In London Friday, the Duchess worked the red carpet at the BOA Olympic Concert dress in an emerald Jenny Packham pleated gown. The design, which featured a low-cut neckline and a sheer, lace back, is accented with a crystal-adorned ribbon that cinched the royal's tiny waist.

She paired the breathtaking dress with her favorite four-inch, $750 Jimmy Choo "Vamp" platform glitter sandals and a matching Jenny Packham bespoke clutch.

The racier-than-normal number wasn't the only new look for the 30-year-old fashion icon, who arrived at the event hand-in-hand with her husband Prince William. Her glossy brunette hair, which is normally styled in her signature bouncy blowout, was pulled back in an elaborate braided chignon that ensured the dress' completely sheer back was on full display.

Tell Us: Do you think this dress was an appropriate look for the royal to wear?