Princess Diana, Naomi Watts Credit: Tim Graham/Getty Images; Neil Mockford/FilmMagic

Double take!

There was no debating that blue was a striking color on the late Princess Diana, and producers for her upcoming biopic seem to agree.

On the set of Diana in London on Wednesday, a princess-playing Naomi Watts was a spitting image of the beloved royal in a bright blue suit reminiscent of the same color-coordinated outfit that Diana wore at a Core Trust event in London on September 19, 1990.

Since filming began in July, the flick's wardrobe department has decked out Watts in several copy-cat looks, including the pink button-down shirt that Diana wore to Sarajevo to meet land mine victims in 1997 and the memorable cerulean one-shoulder dress she donned at a charity appearance in 1996.

"It is such an honor to be able to play this iconic role," Watts, 43, said in February after the casting was announced. "Princess Diana was loved across the world and I look forward to rising to the challenge of playing her on screen."

Directed by Oliver Hirschbiegel and written by Stephen Jeffreys, the film will focus on the last two years in the life of Prince William and Harry's beloved mother; after famously divorcing Prince Charles, Diana reinvented herself as a global humanitarian and was on the path to self-fulfillment before she died at age 36 in an August 1997 car crash.