The Electric Opal and Diamond Tiara Made by Cartier for a Marchioness of Hartington

October babies are blessed with a spectacular and sometimes spooky birthstone, the iridescent and colorful opal. Today, let’s take a closer look at an opal and diamond tiara made for an aristocrat who was a close companion of Queen Elizabeth II.

On her coronation day, Queen Elizabeth II was attended by six beautifully-dressed maids of honor, all daughters of noble families. Helping to direct them was the young Queen’s Mistress of the Robes, Mary Cavendish, the Dowager Duchess of Devonshire. In this portrait, printed as a postcard after the ceremony, Mary stands slightly in the background, between the Queen and Lady Mary Russell.

The decade before the coronation had been a whirlwind for Mary. Born into an aristocratic family of her own, she was Lady Mary Gascoyne-Cecil before her marriage to Edward Cavendish, Marquess of Hartington, who was the son and heir of the 9th Duke of Devonshire. As Marchioness of Hartington, she had five children, including a daughter, Lady Elizabeth, who became a closer friend of both Queen Elizabeth II and Princess Margaret. In 1938, her father-in-law died, and she and her husband became the Duke and Duchess of Devonshire.

A year later, the war intervened. Mary’s elder son, William, was commissioned as an officer in the Coldstream Guards. Just a few months after he married Kathleen Kennedy (sister of John F. Kennedy and Robert F. Kennedy), Billy was killed by a sniper in Belgium. After the end of the war, the family faced another tragedy when Mary’s husband, the 10th Duke, died of a heart attack in 1950. (The attending physician, John Bodkin Adams, was a suspected serial killer, because so many of his patients died while in comas, and many of them left him bequests in their wills.)

The Devonshire dukedom passed to Mary’s second son, Andrew, who was married to Deborah Mitford. Mary, who was just 55 when she became the Dowager Duchess, soon found work to occupy her in her widowhood. She followed in the footsteps of numerous members of her family when she was named Mistress of the Robes to the new Queen Elizabeth II in 1953. Her mother, Cicely, had served as one of Queen Alexandra’s Ladies of the Bedchamber, and her mother-in-law, Evelyn, had been Queen Mary’s Mistress of the Robes.

Queen Elizabeth II made Mary’s appointment official in January 1953, giving her plenty of time to prep for her important role in the upcoming coronation. She supervised the maids as the carried the train of the Queen’s robes during the ceremony. With her robes, Mary wore two particularly spectacular pieces of jewelry. Her tiara, the Devonshire Diadem, was commissioned by the wife of the 8th Duke of Devonshire in 1893. (More on that jewel here.) Her necklace, however, was a special piece from her personal collection.

The necklace, which could also be placed on a frame and worn as a tiara, is set with diamonds and a gorgeous set of black opals. Mary and her husband, then Marquess and Marchioness of Hartington, commissioned the jewel from Cartier in 1937, the previous coronation year. 

In the new book published to accompany the Cartier exhibition at the Victoria & Albert Museum, the source of the opals is revealed: “According to family tradition, the gems, which are of exceptional quality and probably Australian, were supplied by the client, Mary Alice Cavendish—they were a gift from her husband, Edward, Marquess of Hartington, given to her while they were on a government tour of Australia and New Zealand in 1936-37.”

The new opal and diamond jewel was smartly made so that it could be worn in various configurations. Along with the necklace and tiara settings, individual sections of the jewel could be removed and worn as clip style brooches. Mary liked to wear the brooches on her jackets when she attended events during the war. She was frequently seen attending receptions and teas in her role as chair of the Victoria League, an organization that promoted friendship and cooperation between the residents of Commonwealth nations. For her efforts with the Victoria League during the war, she received a CBE from King George VI in 1946.

It’s not known whether Mary wore her newly-completed opal tiara for the coronation of 1937, but she certainly wore it as a necklace for the coronation of 1953, and for numerous gala events and state occasions in the years that followed. She served as Mistress of the Robes until 1967. Currently, the tiara setting of the jewel is one of many on display in the final room of the Cartier exhibition at the V&A. You can see it yourself for a few more weeks—the exhibition closes on November 16!