Kristen Stewart said it was 'spooky' to film scenes in a replica of Princess Diana's wedding dress for 'Spencer'

• Kristen Stewart plays Princess Diana in the biopic "Spencer."
• She filmed scenes in a replica of the late royal's wedding dress.

Kristen Stewart shared what it was like to wear a replica of Princess Diana's wedding dress while filming "Spencer" on Tuesday.

Stewart attended the Los Angeles premiere of the Pablo Larraín-directed biopic on Tuesday at the DGA Theater Complex.

The film, which received a five-minute standing ovation at the Venice Film Festival, takes place during the royal family's Christmas vacation at Sandringham House in 1991 and depicts the downfall of Prince Charles and Diana's marriage.

Wearing a Chanel two-piece, Stewart spoke to Entertainment Tonight's Lauren Zima about one of the most intense experiences of the filming process: portraying Diana's wedding day.

"Even though the movie takes place over a three-day period and even though I play her as a speculatively 29, 30-year-old person, we still wanted to give a taste of the scope of her life," Stewart told ET. "And the wedding dress is embedded in that montage and putting that on was a spooky day."

As Stewart said to Zima, the film does not actually contain a scene of Diana and Charles getting married, but Larraín did film the actress wearing a replica of Princess Diana's famous wedding dress outside of a castle.

"I was like, 'Wait, but this is so particular,'" she said. "This actually does land on a very precise day of her life."

Stewart went on to say that Larraín told her: "What does it feel like to believe in an ideal that then becomes very, very apparently farcical? It's kind of just like, let your heart break in a moment."

"I was like, 'OK got it. Let's go,'" she said.

Larraín also told ET that he thought Stewart was "scared" when filming in the wedding gown.

"I think when she wore it, she was, she had mixed feelings," Larraín said to ET of Stewart's experience wearing the dress, which was created by costume designer Jackie Duran.

"She was scared and excited, which also worked for the character as we were shooting," he added to ET. "I think that's exactly what's in the movie."

"Spencer" premieres in theaters on November 5.