Jessica Biel's New Ring - Is It a Movie Prop?

Jessica Biel

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Jessica Biel has some new bling, but don't get too excited: It's not from Justin!

The actress, who has yet to be spotted wearing an engagement sparkler, was sporting a ring on the set of her new movie Emmanuel and the Truth About Fishes, filming in L.A. Friday, but it's just for the role.

The thriller, which also stars Alfred Molina, is reportedly about a woman who develops an obsession with her new neighbor who resembles the woman's dead mother.

Off-camera, Biel has been noticeably spotted without any engagement ring. At the Golden Globes, she wore a ton of Tiffany & Co. jewelry including a diamond ring in platinum but her left ring finger was bare. The actress made other public appearances, including a party at the Chateau Marmont, sans ring that weekend as well.

Timberlake, 31, proposed to Biel, 29, during the couple's annual vacation in Montana with a custom-designed ring, a source confirmed to PEOPLE in January.