Cameron Diaz’s latest accessory sparked some engagement rumors.

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The 42-year-old attended the Academy's Hollywood Costume luncheon Wednesday in Los Angeles and looked classy in a black knee-length dress, but most of the attention was placed on her gold ring. Although it wasn’t a traditional engagement sparkler, it was worn on her wedding finger. Does this mean her beau Benji Madden proposed?

During the luncheon, Diaz was "casually and constantly twirling her ponytail, showing off the ring and often playing with it," an insider told People.

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Later that day, the couple also met some friends for dinner at Madeo in Beverly Hills."They arrived together with Benji driving. Cameron showed off her new ring and was smiling," a source said. "They enjoyed dinner for several hours."

Diaz and the Good Charlotte rocker were first linked in May. The relationship seemed to heat up quickly when Madden, 35, met Diaz’s family in July and moved in with the Sex Tape actress shortly after, according to the magazine. Sources revealed that they’ve even discussed getting married.

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

Nicole Richie, who is married to Madden’s brother Joel, was asked about the romance when she appeared on Watch What Happens Live in July.

“I approve of anything that's going to make Benji happy,” she said. "I am a devoted sister-in-law and I am happy for anyone who is happy.”

Tags: Cameron Diaz Benji Madden