Louise Roe and Josh Slack Credit: twitter.com

Louise has a whole lotta bling!

Announcing her engagement to her Abercrombie & Fitch model boyfriend of two and a half years, Josh Slack, Dec. 5, Fashion Star host Louise Roe proudly showed off her new engagement bling via Twitter.

"I was given my great-grandmother's aquamarine ring, I love!" the 31-year-old tweeted along with a picture in which she is modeling the ring while hugging Slack, 24.

Though Slack got down on one knee with the family heirloom, he and Roe intend to choose a new ring together later in their engagement.

Speaking to England's Fabulous magazine in July, Roe -- who hosted the CW's short-lived makeover series Plain Jane -- said she was anxious to walk down the aisle and start a family. "Lots of my friends are getting engaged -- they're dropping like flies!" she told the magazine. "My two older sisters are mummies and I'd love kids running around one day, too."

Prior to replacing Elle Macpherson on Fashion Star, Roe was best known in the U.S. for appearing on season 2 of MTV's The City alongside Olivia Palermo, Whitney Port, Erin Kaplan and Roxy Olin.