Cameron Diaz has caused much speculation over her and Benji Madden's relationship as it is now rumoured that the pair have become engaged after the Hollywood actress was recently photographed wearing a sparkly, gold ring.

Cameron Diaz
Diaz arriving at the Hollywood Costume exhibition luncheon

Diaz was spotted wearing the new piece of bling on her left hand on Wednesday (Oct 8th) in Los Angeles while attending the Hollywood Costume exhibition luncheon, this has led many people to think that she will finally tie the knot in the near future.

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An eyewitness attending the event told People magazine that Diaz was "casually and constantly twirling her ponytail, showing off the ring and often playing with it" during the evening. The couple then enjoyed a dinner with friends at Italian restaurant Madeo, in Beverly Hills.

"Since she started dating Benji, Cameron has changed in a very positive way. She can't stop smiling and seems much happier," a source also told the mag. "Benji has lived with Cameron for the past couple of months. They act like they can't get enough of each other and spend a lot of time together. During the days, they often share a workout. At night, they often stay at home and cook."

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The 42 year-old actress and the Good Charlotte rocker, whose relationship first became public knowledge back in May, are "openly acknowledging to friends that they see a long future together, and yes, marriage may be a part of that plan," an insider told E!News in July.

Benji mADDEN
Has Benji Madden proposed to Diaz?

Both stars have yet to confirm nor deny if they are preparing to walk down the aisle.