Credit: © Maison du Grand-Duc

On Tuesday 1 July 2025, the Maison du Grand-Duc presented the official monogram of the future Grand Duke Guillaume, which will be used formally from Friday 3 October 2025.

The monogram consists of two symmetrical letters "G", mirroring each other and surmounted by a crown. It will appear on the uniforms of the Luxembourg Army, the Grand Ducal Police, the Prison Administration, the Customs and Excise Agency and the Grand Ducal Fire and Rescue Corps (CGDIS) and will serve as the official symbol of the future Grand Duke.

The Maison du Grand-Duc explained that the creation of this new monogram is based on a historical analysis. Four cases were identified:

  • double first names with symmetrical initials (Marie-Adélaïde);
  • single first names with non-symmetrical initials (Jean);
  • single first names with symmetrical initials (Henri);
  • as an exception, single first names with two non-symmetrical letters, uppercase "C" and lowercase "h" (Charlotte).

A symmetrical letter is a letter whose reflection in a mirror remains unchanged.

While purely graphic additions were incorporated into the monograms for Grand Duchess Marie-Adélaïde, Grand Duchess Charlotte (Marie-Adélaïde's sister and Guillaume's great-grandmother) and Grand Duke Jean (Charlotte's son and Guillaume's grandfather), there was no need for such additions for the monogram of Grand Duke Henri (Guillaume's father and the current Grand Duke of Luxembourg).

The Maison du Grand-Duc asked Luxembourg graphic designer Yolande Kaiser (yo.ko.graphics) to stylise the "G" of the future Grand Duke, thus reviving the tradition of non-symmetrical mirror letters.

Yolande Kaiser explained: "Prince Guillaume opted for a G style inspired by italic handwriting. Based on this calligraphic orientation, several sketches were developed, taking into account both practical considerations - such as the use of the monogram as a badge on uniforms - and the specific wishes of Prince Guillaume and Princess Stéphanie. One of the key elements for the Prince was that the letter G should be immediately recognisable. To enhance this feature, elements of the letter's curve were incorporated inside the monogram, adding a decorative and airy touch. Designed according to the principles of the golden ratio, the monogram subtly widens upward towards the crown. The outer edges of the crown and the double G are perfectly aligned, reflecting a concern for geometric harmony. The crown itself has been redesigned for the occasion, faithfully respecting the official crown of the Grand Ducal Court. For the insignia intended for uniforms, the crown rests on top of the G."

The monogram is accompanied by a complete graphic charter. Any reproduction of the monogram is subject to prior authorisation from the Maison du Grand-Duc.

Prince Guillaume, Hereditary Grand Duke of Luxembourg, is set to succeed his father as Grand Duke on 3 October 2025.