In an interview for Hello! magazine, the 28-year-old designer confessed she designed her own ring to "look like an earring that [her] father wore."
"I used to hold my finger up to his ear when I was little and say: 'I want a ring like that'. Now I have one!" she told the magazine.
Osbourne and Mosshart met at the 2011 wedding of Kate Moss and Jamie Hince.
According to Mosshart, he proposed on a balcony that overlooks the ocean in Anguilla.
"She said yes! And then she smiled for the rest of the night!" he said adding, "I knew she was 'the one' pretty early on."