Bestselling author Jackie Collins died Sept. 19
Credit: Fred Duval/FilmMagic

Joan Collins is staying strong after losing her beloved sister Jackie to breast cancer.

The actress looked glamorous as ever in a shimmery dress and black fur on the red carpet Tuesday at the BFI Luminous Fundraising Gala at The Guildhall in London.

Bestselling author Jackie died Sept. 19 at the age of 77 after keeping her illness a secret for more than six years. She revealed her battle to PEOPLE in what would be her last interview.

Joan, 82, previously told PEOPLE she was “completely devastated” by Jackie’s death.

“She was my best friend,” she said. “I admire how she handled this. She was a wonderful, brave and a beautiful person and I love her.”

The dame next appears on The Royals, playing the Grand Duchess Alexandra of Oxford for four more episodes in season 2.

“She’s brilliant, and horrific as well!” her costar Elizabeth Hurley recently told PEOPLE of the character. “She does some fabulous things and of course looks phenomenal.”

The Royals airs Nov. 15 at 10 p.m. ET on E!