Princess Ragnhild (center) wears the tiara at the wedding of her brother, Crown Prince Harald, 29 August 1968 (STRINGER/AFP/Getty Images)

The royal tiara collection of Norway has been enriched over the years largely by contributions from two important women: the present king’s grandmothers, Queen Maud of Norway and Princess Ingeborg of Sweden. Today, we’re looking at the delicate circle tiara from Ingeborg’s collection.

Princes Ingeborg had links to numerous European countries and royal families. Daughter of King Frederik VIII of Denmark, Ingeborg married Prince Carl of Sweden. Their children then married into the royal families of Norway, Denmark, and Belgium. Today, the sovereigns of Belgium, Norway, and Luxembourg are all Ingeborg’s direct descendants.

But although she had such significant royal links, this tiara wasn’t an heirloom. Instead, it was purchased for her by Prince Carl from Boucheron, following the firm’s showing of the tiara at the Exposition Universelle, held in 1900 in Paris. The delicate piece features interlocking diamond circles set in platinum; the large pearl button-style elements at the front of the tiara were reportedly later additions. Ingeborg wore the tiara until the very end of her life. In the photo above, she wears it for the 21st birthday celebrations for her grandson, Crown Prince Harald of Norway, in February 1958. She died only a few weeks later.

Crown Princess Martha and Crown Prince Olav attend a banquet at the Waldorf-Astoria Hotel in New York, 2 May 1939

Ingeborg was a generous sharer of jewels during her lifetime, including the circle tiara. In 1939, she lent several jewels to her daughter, Crown Princess Martha of Norway, ahead of her visit to America. Martha wore the circle tiara for a banquet held at the Waldorf-Astoria Hotel in New York City in May 1939. On that occasion, papers reported that she paired her mother’s tiara with “a silver lame gown with a shallow, gathered bodice and simple molded waist and hipline,” which was decorated on one shoulder with white orchids.

The tiara was also worn by Ingeborg’s eldest daughter, Princess Margaretha of Denmark. She chose the circle tiara for a family portrait with her husband, Prince Axel, as well as their two sons and their spouses, taken in the 1950s.

The tiara was eventually passed down to Ingeborg’s granddaughter, Princess Ragnhild of Norway. She wore the tiara frequently at gala events, seeming to prefer the light, delicate sparkler to the grander tiara that she inherited from Queen Maud. In 1968, Ragnhild wore the circle tiara for a very important family occasion: the wedding of her brother, the future King Harald V, to Sonja Haraldsen. (We just covered the jewels of their wedding here!)

Princess Ragnhild (center, wearing green) wears the tiara at the wedding of her nephew, Crown Prince Haakon, 25 August 2001 (AFP/Getty Images)

Ragnhild repeated the tiara for the wedding of the next crown prince, her nephew, Crown Prince Haakon, in 2001, attending in bejeweled splendor even though she would later criticize his choice of bride in a television appearance. Ragnhild made her home in Rio de Janiero, so her tiara appearances were rather infrequent near the end of her life. When she died in 2012, the circle tiara was inherited by her children. We haven’t heard any news about their plans for the family heirloom — at least not yet!