In The Queen’s Fashion: What Marie Antoinette Wore to the Revolution, Caroline Weber examines the queen’s choices for fashion on May 4th and 5th, during the opening of the Estates General:
[For the event, Marie Antoinette] abandoned her more personal whims of style for the time-honored conventions of queenly pomp. For the formal procession and the religious services on May 4th, 1789, she settled on a lustrous cloth-of-silver gown, which viewed beside Louis XVI’s resplendent cloth-of-gold jacket, would cast her as “the moon to the King’s sun.” … both she and Louis XVI would emphasize the Bourbon gloire by wearing the most precious white diamonds in the crown’s collection. … her husband would wear the so-called Pitt or Regent diamond affixed to his hat, while Marie Antoinette would [wear] the legendarily flawless Sancy diamond.
For the opening of the Estates General on May 5, Marie Antoinette chose [a dignified ensemble that would present] her as an avatar of an entire, august class rather than a lone, untamed consort … she commissioned Rose Bertin to supply her with “what was to be the last of her grand gala dresses … a dress of purple satin over a white skirt embroidered with diamonds and pailettes.” … She decided to accessorize this glorious confection with only a clutch of white ostrich feathers and a single band of diamonds in her hair. Unlike the modest gown she had worn to the Invalides of June of the previous year, her garb for the Estates General would remind everyone present that … she remained every inch their transcendent Queen, divine Bourbon dazzle incarnate.
image: Jane Seymour in La Revolution Francaise, my screencap