Is Cameron Diaz planning a trip down the aisle?

The 42-year-old "Sex Tape" actress who has reportedly been dating Good Charlotte rocker Benji Madden, was spotted with a gold ring on her left finger at the Hollywood Costume luncheon in Los Angeles on Wednesday, according to Us Weekly.

The actress was spotted wearing that same piece of jewelry during a romantic dinner with Madden. An eyewitness said Diaz was "casually and constantly twirling her ponytail, showing off the ring and often playing with it," People Magazine reports.

The couple has not commented on the meaning behind Diaz's ring.

Diaz and Madden have been dating since April this year after being set up by Madden's sister-in-law Nicole Richie. According to E! News, a source claimed that the couple were "openly acknowledging to friends that they see a long future together, and yes marriage may be a part of that plan."

The actress introduced her rumored boyfriend to her family during the Fourth of the July weekend and the two were spotted getting cozy at a beach outing. Diaz's mother, Billie, is reportedly excited to have Madden join her family.

"Billie has been gushing about Cameron's new relationship," an insider told Us Weekly. "She absolutely loves Benji and she hopes this is the man her daughter will finally settle down with."

The couple has reportedly moved in together, according to AZCentral.

''Benji has lived with Cameron for the past couple of months," a source said. "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."

''For a girl who was happy being single, Cameron seems to have fallen in love. She is really happy. The relationship is deep and she wants people to know it.''