Louise has a whole lotta bling!
"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."