Princess Madeleine of Sweden wears the Aquamarine Kokoshnik (Pascal Le Segretain/Getty Images)

March is the month of the aquamarine, and we’ll be celebrating some of the grandest royal aquamarine tiaras each Saturday this month. We’re kicking things off with one of my very favorites: the aquamarine kokoshnik owned by Sweden’s Princess Margaretha.

Princess Madeleine of Sweden wears the tiara at the 2015 Nobel Prize Ceremony (Pascal Le Segretain/Getty Images)

It’s said that this tiara originally belonged to Margaretha’s grandmother, Margaret of Connaught, who was the first wife of King Gustaf VI Adolf of Sweden. The tiara also has a coordinating aquamarine and diamond brooch. The set was supposedly a later addition to Margaret’s jewelry collection, not one of her wedding gifts. The maker of the tiara is unknown, although I see similarities in the diadem to pieces made by Koch, a German court jeweler. Both the tiara and the brooch feature absolutely enormous aquamarines; the tiara places delicate lattice-like diamond elements in between the large blue stones to form the traditional kokoshnik shape.

Princess Sibylla wears the tiara at her pre-wedding gala in 1932 (Wikimedia Commons)

We’re probably all familiar with the tragic story of Margaret of Connaught’s death, which led to the division of her jewels among her children. If this piece was indeed a part of her collection, it was inherited by her eldest son, Gustaf Adolf, who was expected one day to become king. His wife, Princess Sibylla of Saxe-Coburg and Gotha, debuted the tiara at a ball ahead of their civil wedding in Coburg in 1932. Sibylla wore the aquamarines throughout her lifetime, even after the untimely death of her husband in a 1947 plane crash. She was the de facto first lady of Sweden following the death of Queen Louise, and she was regularly bedecked in jewels.

When Princess Sibylla died in 1972, the aquamarines were inherited by her eldest daughter, Princess Margaretha. She had worn the tiara even before Sibylla’s death; above, you can see her wearing the tiara in 1964. As a young woman, Margaretha wore the tiara on many occasions, including at the wedding of her youngest sister, Princess Christina, in 1974. Margaretha’s daughter, named Sibylla for her grandmother, also wore the heirloom tiara for her own wedding to Baron Cornelius von Dincklage in 1998.

Princess Margaretha wears the tiara at the wedding of Crown Princess Victoria in 2010 (Pascal Le Segretain/Getty Images)

After the 1998 wedding, there was a long stretch of time where the aquamarines were not seen in public. Many feared that they had been sold. And then, in June 2010, Princess Margaretha unexpectedly appeared at the wedding of her niece, Crown Princess Victoria, wearing both the aquamarine tiara and the coordinating brooch.

The tiara was apparently a last-minute choice for Victoria’s wedding; in the press release sent out by the royal court detailing the history of the jewels worn by the king’s sister, Margaretha was noted as wearing the Baden Fringe Tiara. (She did eventually wear the fringe at a Swedish royal wedding — Princess Madeleine’s nuptials in 2013.) There were persistent rumors, however, the the tiara was sold — and that the buyer was Margaretha’s brother, the king. This theory was bolstered in 2014 when her sister, Princess Christina, wore the tiara at the representatives’ dinner in Stockholm.

Princess Margaretha wears the tiara and brooch at the wedding of Prince Carl Philip in 2015 (Ian Gavan/Getty Images)

However, Princess Christina has said publicly that Margaretha does still own the tiara but now keeps it in the vaults in Sweden with the rest of the Bernadotte jewels, where the rest of the members of the family have access to it. As Margaretha lives a quiet life in the English countryside, it certainly makes much more sense for other members of the family to get more use out of the piece. Margaretha only wears gala jewels these days when she visits Sweden, so the tiara is there for her to use when she wants, as she did for Prince Carl Philip’s wedding in June 2015.

Princess Madeleine wears the tiara at the 2015 Nobel Prize Ceremony (Pascal Le Segretain/Getty Images)

And Princess Madeleine has done just that: since December 2015, she has worn her aunt’s tiara at the Nobel Prize ceremony, at a tea party for sick children, in an official portrait, and for a state banquet.