Mila Kunis and Ashton Kutcher are reportedly engaged.

The actress was spotted wearing a giant diamond sparkler on her ring finger while out shopping with her mother at outdoor mall The Grove in Los Angeles on Thursday, sparking speculation her boyfriend of almost two years has proposed.

"She is crazy about him!" added a source, confirming the news.

The Ted star, who is notoriously private about her love life, also uploaded an adorable picture of her and Ashton grinning ear-to-ear on Instagram the previous day along with the words, "I love you @kutcher78."

Fans were quick to congratulate the couple - who first met 16 years ago on the set of That 70's Show - enthusing, "Congrats on your engagement!" and "Jackie and Kelso congrats."