The only thing that could take your eyes away from examining Sienna Miller's baby bump might be the bling on her finger.

The reportedly pregnant actress was photographed sporting a sparkling vintage rock on the ring finger of her left hand while leaving London's Groucho Club Friday night, Life&Style reported, prompting speculation that she is now engaged to boyfriend Tom Sturridge.

PHOTOS: Bling Bling! Top Five Celeb Engagement Rings

Miller, 30, has not confirmed or officially announced that she is engaged to Sturridge, 26, whom she has been dating for a year. Her rep could not immediately be reached for comment.

She and Sturridge are expecting their first child, Us Weekly first reported in January. Miller's sister Savannah Miller tweeted last month that she was, "THRILLED," which many have interpreted as a nod to Sienna Miller's big pregnancy news.

The stylish actress is known for her trendsetting fashion choices and for her on-again, off-again public relationship with actor Jude Law. The pair got engaged in December 2004, split for the first time in 2006 - following his infidelity with the nanny of one of his children, reunited in 2009, and dated for two years. They split again, seemingly for good, in February 2011.

Miller began dating Sturridge soon after she and Law parted ways.

Life&Style Magazine reported that the couple got engaged last month, citing an unnamed source who also said that Sturridge proposed on a trip to Paris over Christmas.