Hollywood stars Ashton Kutcher and Mila Kunis are engaged after dating for nearly two years, People.com reported. Kunis was spotted wearing a diamond on her ring finger while shopping with her mother Thursday. "Ashton and Mila have talked about getting married for quite a while," a source told the magazine in December. No other details regarding the couple's engagement or whether they have set a wedding date were immediately available. Kutcher's divorce from actress Demi Moore was finalized last November. Kutcher and Kunis co-starred in the sitcom "That '70s Show," which ran from 1998 to 2006.