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Earlier this week, Princess Caroline of Monaco celebrated her birthday. To mark the occasion, we’ve got a closer look at her favorite sparkler: the diamond and pearl tiara that belonged to her grandmother, the late Princess Charlotte, Duchess of Valentinois.

Princess Caroline wears the tiara in Luxembourg, October 2012 (Sean Gallup/Getty Images)

The intricate diamond, gold, and platinum tiara, which features large pearl drops suspended en tremblant from elaborate arches, was made by Cartier for Princess Charlotte of Monaco. It’s often said that the tiara was a wedding gift to the princess from her new husband, Count Pierre de Polignac. However, that’s not true. Although Charlotte and Pierre stuck it out long enough to have two children, Prince Rainier and Princess Antoinette, they divorced in 1933, years before the tiara was even made. Charlotte herself apparently ordered the tiara from Cartier in 1949, the same year that her son became the principality’s ruler.

Princess Charlotte stands beside her son, Prince Rainier III, during his enthronement ceremonies, April 1950 (CSU Archives/Everett Collection Historical/Alamy)

Charlotte really should have been the sovereign princess of Monaco in her own right. Although she was the illegitimate daughter of Prince Louis II and an Algerian cabaret singer, Louis (who had no legitimate heirs) legally adopted her, which legitimized her and placed her directly in line to the Monegasque throne. But in 1944, when her son Rainier turned 21, Charlotte officially ceded her rights to the throne. When Louis II died five years later, it was Prince Rainier III who took over in Monaco, not his mother. (Instead, she got a college degree and then retired to an estate in France with her jewel-thief lover. I mean, who wouldn’t, right?)

Princess Charlotte wears the tiara at Prince Rainier and Princess Grace’s pre-wedding gala at the opera, 1956

Charlotte continued to wear the tiara throughout her life; she donned it during the celebrations for the wedding of her son, Prince Rainier, in 1956. Rainier’s wife, Grace Kelly, brought an incredible amount of glamour with her when she moved to the tiny principality, but she never wore her mother-in-law’s Cartier tiara in public. The only Grimaldi women who have been photographed in the tiara are Princess Charlotte and Princess Caroline, Charlotte’s granddaughter. Caroline has worn it for major white-tie events, and she even donned it for a series of Casiraghi family portraits taken shortly before the death of her husband, Stefano.

The pearl drop tiara is exhibited beside jewels from the collection of Princess Grace (including the Bains de Mer Tiara, the Diamond Festoon Necklace, and her diamond engagement ring) during the landmark Cartier exhibition in Canberra, 2018 (Photo generously shared by Javier)

Because she’s been the primary wearer of the piece for so many years, some have speculated that Caroline inherited the tiara from her grandmother. It seems more correct to say, however, that the piece is owned by the Grimaldis more generally, and that Caroline “borrows” it from the family’s collection. Catalogue notes from Cartier exhibitions have described the tiara as being owned by the “Palais Princier de Monaco collection,” suggesting that the Grimaldis have placed their jewels (and probably their art and other values) in a kind of family trust — but one that allows family members like Caroline to continue to use them. I really hope this is indeed the case. I am a major proponent of jewel foundations, especially those that allow various members of the family to borrow pieces from the collection, as they allow jewels to be seen and worn without the threat of sale that inevitably accompanies personal ownership.

Caroline wears the tiara in Luxembourg, October 2012 (Andreas Rentz/Getty Images)

The tiara was most recently worn by Caroline during the 2012 pre-wedding dinner for Hereditary Grand Duke Guillaume of Luxembourg. Since then, it has mostly often been seen as part of a traveling museum exhibition devoted Princess Grace. Confusingly, that exhibition describes the tiara as being one of Grace’s jewels, even though (to my knowledge) there are no photographs of her wearing it. But Cartier notes that after Charlotte ordered the tiara, it was worn by “several princesses of Monaco on various occasions,” so it’s possible that she wore it privately. Really, though, what I want to know is this: are we ever going to see the current Princess of Monaco take this gorgeous heirloom piece out for a spin?