Spears shows off engagement ring on Las Vegas trip

Britney Spears showed off her new engagement ring over the weekend (17-18Dec11) as she treated her fiance Jason Trawick to a 40th birthday party in Las Vegas.

The agent proposed to the Toxic hitmaker in front of her sons Sean Preston, six, and Jayden James, five, earlier this week (end18Dec11).

And Spears couldn't wait to show off her new diamond as she posed for photographs holding up her left hand as she cuddled and kissed Trawick during his birthday bash.

The couple celebrated Trawick's milestone birthday at Sin City's Chateau Night Club, where he was presented with a large cake.

In a series of posts on Twitter.com, Spears writes, "Still glowing! About to jump on a plane to Planet Hollywood in Vegas. Throwing a Bday Party for Jason at Chateau Night Club. So fun.

"Tonight was one of the most magical nights of my life. Such an amazing time with my new fiance and our closest friends and family. Blessed."