The black evening dress worn by Princess Diana on the night her estranged husband, then-Prince Charles, now King Charles III, publicly acknowledged his infidelity is going up for auction for the first time.

The silk dress, designed by Christina Stambolian and widely known as Diana’s “revenge dress,” is expected to sell for between $150,000 and $300,000 at Sotheby’s in New York on Dec. 9, according to a press release.

Diana wore the dress to a fundraising dinner hosted by Vanity Fair at London’s Serpentine Gallery on June 29, 1994.

Her appearance came on the same evening that a nationally televised documentary aired in which Charles admitted that he had been unfaithful during their marriage.

The couple had been separated for nearly two years at the time.

Diana’s arrival in the fitted black dress before a crowd of photographers became one of the most widely recognized images of her and a defining moment in modern fashion history.

The outfit was soon dubbed the “revenge dress” by the media, with her decision to wear it seen as a public display of confidence at a time when details of her marriage were under intense scrutiny.

The off-the-shoulder dress features a pleated bodice, an asymmetric hemline and a dramatic chiffon train. Diana paired it with black heels and a clutch, as well as a pearl choker centered on an antique sapphire-and-diamond brooch given to her as a wedding gift by the Queen Mother.

Diana had owned the dress for three years but had previously considered it too daring for a public appearance. She reportedly made a last-minute wardrobe change ahead of the dinner, setting aside a more traditional Valentino gown.

According to her stylist at the time, Anna Harvey, Diana “wanted to look a million dollars.”

Morgane Halimi, Sotheby’s global head of handbags and fashion, said Diana understood that clothing could serve as a form of communication.

“On her own terms, Princess Diana turned the dress into one of the most powerful messages she ever made,” Halimi said.

The image helped establish the idea of “revenge dressing,” a term now used to describe clothing chosen to project confidence, transformation or independence after a breakup or personal crisis.

Diana included the Stambolian dress among the 79 outfits she personally offered at a charity auction in June 1997, shortly before her death that August.

The sale raised funds for cancer and AIDS charities, and the dress was purchased by its current owners, who have kept it ever since.

A rare copy of the original 1997 auction catalogue, numbered and signed by Diana and Stambolian, will be sold with the dress. The catalogue credits Diana’s son, Prince William, with suggesting the original charity sale.

Part of the proceeds from the December auction will be donated to NHS Lothian Charity on behalf of the Royal Edinburgh Hospital.

Before the sale, the dress will go on an international exhibition tour. It will be displayed at Sotheby’s in London from Sept. 18 to 24 during London Fashion Week before traveling to Hong Kong and Geneva.

It will then be exhibited at Sotheby’s Breuer Building in New York from Dec. 2 ahead of the live auction on Dec. 9.

The original dress has not been displayed publicly for nearly 30 years, although replicas have appeared in exhibitions and television productions, including Netflix’s royal drama The Crown. (AA)