Queen Mary faces one royal jewelry rule before her highly anticipated reunion with Queen Mathilde

Mary of Denmark’s royal jewelry collection is set to take center stage once again as she reunites with Queen Mathilde of Belgium during an upcoming state visit that is already generating excitement among royal fashion watchers.

King Frederik X and Queen Mary of Denmark will pay a state visit to Belgium from September 8 to 10, 2026, at the invitation of King Philippe and Queen Mathilde. 

The three-day trip will highlight the close relationship between the two European monarchies while also offering one of the year’s most anticipated royal fashion moments, with gala tiaras and historic jewels expected to be on full display.

A major royal reunion in Belgium:

The visit follows Belgium’s 2017 state visit to Denmark and serves as the official return visit between the two royal families. It will also reunite two of Europe’s most admired royal style icons, Queen Mary and Queen Mathilde, whose elegant evening looks and tiara choices consistently attract international attention.

The program will begin on September 8 with an official welcome ceremony at the Royal Palace of Brussels, followed by meetings with Belgium’s prime minister, members of the Federal Parliament, and the mayor of Brussels before a traditional state banquet at the Royal Castle of Laeken.

© HENNING BAGGER

On September 9, the Danish royals will travel to Wallonia to visit the Lauzelle Forest alongside researchers from the University of Louvain before returning to Brussels for meetings with Danish business representatives and celebrations marking the 50th anniversary of the Danish Church in Brussels. The day will conclude with the traditional return dinner hosted by the Belgian royal family.

The final day, September 10, will take the delegation to Flanders, where they will explore Antwerp’s urban transformation, attend a reception aboard the royal yacht Dannebrog, tour the port, and participate in the official farewell ceremony.

Why Mary can’t wear Denmark’s most famous royal jewels abroad:

Although the visit promises an impressive display of royal diamonds, Queen Mary faces one unique limitation that sets the Danish monarchy apart from many other European royal houses.

© Danny Martindale

Denmark possesses one of the world’s most spectacular royal jewelry collections, but some of its most iconic pieces belong to the Danish State rather than the royal family personally. Because they are state property, these historic jewels are required to remain in Denmark at all times and cannot accompany the Queen on overseas visits.

Among the most famous is the spectacular Emerald Parure, one of the Danish monarchy’s most treasured collections. Dating back to 1840, the emerald set was created to commemorate the silver wedding anniversary of King Christian VIII and Queen Caroline Amalie. Since it is part of the Danish Crown Jewels, Queen Mary is prohibited from wearing it outside the country.

© KELD NAVNTOFT

The same restriction also applies to the celebrated Midnight Tiara, another state-owned treasure that must always remain in Denmark.

What jewelry Mary is expected to wear instead:

Fortunately for royal fashion fans, the restriction applies only to Denmark’s state-owned jewels.

Queen Mary still has access to pieces from the Danish royal family’s entailed collection as well as her own personal jewelry collection. That means she can still choose from several of the dynasty’s most recognizable tiaras and heirloom pieces for the state banquet at Laeken Castle.

© Julian Parker/Mark Cuthbert

The glamorous occasion has also fueled speculation that Mary could debut a previously unseen jewel or unveil a piece that has remained tucked away in the royal vaults, making the September visit one of the most anticipated royal fashion events of the year.

With Queen Mathilde, Princess Elisabeth, and Queen Mary all expected to attend the state banquet, royal jewelry enthusiasts will be watching closely to see which dazzling tiaras and historic heirlooms take the spotlight.