Queen Mary's Diamond Lozenge Tiara

Princess Margaret wears the tiara during the celebrations for the inauguration of Queen Juliana of the Netherlands, 6 Sep 1948 (Dutch National Archives/Wikimedia Commons)

When the Duchess of Sussex unearthed Queen Mary's Diamond Bandeau for her wedding earlier this year, royal jewel lovers rejoiced. But get excited, because there is very likely another diamond bandeau from Mary's collection still extant in the vaults: her Diamond Lozenge Tiara.

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Queen Mary acquired the tiara -- a low, sleek kokoshnik-shaped tiara made of diamonds set in a lozenge pattern and topped with 13 pearls -- sometime before 1935. That December, she wore the tiara for her very first film premiere appearance. She attended the debut of The Ghost Goes West in Leicester Square alongside the Duchess of Kent on December 17, still clad in deepest mourning following the death of her sister-in-law, Princess Victoria.

You'll also often see a photograph of Mary wearing the tiara with a white fur. That image was taken four years later, when Mary attended a performance by the Comédie-Française at the Savoy Theatre on March 1, 1939. On that occasion, she was accompanied by the French ambassador, Monsieur Corbin, and Lady Bessborough.

Princess Margaret wears the tiara during the celebrations for the inauguration of Queen Juliana of the Netherlands, 6 Sep 1948 (Dutch National Archives/Wikimedia Commons)

A decade later, Mary loaned the tiara (sans its pearl toppers) to her granddaughter, Princess Margaret. The princess, who had just turned 18, was headed to the Netherlands for the inauguration of Queen Juliana. (By tradition, monarchs don't attend each others' coronations/inaugurations, sending their heirs instead. Margaret attended because her sister, the future Queen Elizabeth II, was pregnant with her first child, Prince Charles.)

Accompanied by the Earl and Countess of Athone (who was a cousin of Juliana), Margaret packed the Cartier Halo Tiara and the Diamond Lozenge Tiara in her luggage as she headed to Amsterdam. It was Margaret's first trip to the continent and her first official engagement outside Britain.

Princess Margaret wears the tiara during the celebrations for the inauguration of Queen Juliana of the Netherlands, 6 Sep 1948 (Dutch National Archives/Wikimedia Commons)

Margaret, who was ranked fourth in precedence among the royal guests, paired the Diamond Lozenge Tiara with pearls for a "sports fantasy" showcase at Amsterdam's Olympic Stadium following the inauguration. (She chose the Halo Tiara for a concert held the following evening.)

This tiara hasn't been seen in public for a little more than half a century, but I have significant hope that this petite sparkler still resides in the royal vaults today. Here's hoping we see one of the younger princesses take this tiara out for a spin soon!