Pippa Middleton and stockbroker boyfriend Nico Jackson attended the Sugarplum Ball (yep, Sugarplum) last night in London. The Duchess of Cambridge's younger sister donned a sexy sheer black gown with intricate embroidery on the bodice.

She buttoned up against the cold in a sparkly black shrug, but quickly removed the shrug when she got to the ball so she could show off the floor-length dress. Even though the dress was daring -- complete with a semi-sheer skirt -- the royal family would be proud of Pippa's modesty as the top of the dress was definitely lined.

Kate's sister has had some hits and misses in the style sphere over the years, but we think this look was a big hit. She wore her hair up in a pretty classic updo -- with small braids throughout. The lovebirds looked happy as can be, but still no ring on Pip's left hand.

We think it's only a matter of time!

Click through the gallery above to see Pippa's stunning dress.