Princess Mabel (left) and Princess Beatrix (right) of the Netherlands attend the Royal Netherlands Society of Engineers (KIVI) 2016 Prince Friso Engineering Award ceremony in Delft on March 16, 2016. The award is named for Dutch prince Johan Friso, who was the son of Princess Beatrix and husband of Princess Mabel. The prince was seriously injured in a skiing accident in 2012 and died in 2013.
King Willem-Alexander and Queen Máxima of the Netherlands attend a New Year's reception for the diplomatic corps at the Royal Palace of Amsterdam on January 13, 2015.
Princess (formerly Queen) Beatrix of the Netherlands attends the funeral of Germany's former president Richard von Weizsäcker in Berlin on February 11, 2015. (Photos by Georg Hilgemann – Pool/Getty Images)
King Willem-Alexander and Queen Maxima of the Netherlands arrive at the Royal Palace of Amsterdam on January 14, 2015 for their traditional New Year's reception for foreign diplomats (Photos by Koen van Weel/AFP/Getty Images)
Princess Beatrix of the Netherlands arrives at the Norwegian Church in Rotterdam on November 13, 2014 to attend the yearly Christmas market. (Photo by BAS CZERWINSKI/AFP/Getty Images)
King Willem-Alexander of the Netherlands; his wife, Queen Máxima; and his mother, Princess Beatrix, arrive at RAI Convention Center in Amsterdam on November 10, 2014 to attend a national commemoration for the victims of the Malaysia Airlines flight MH17 disaster, which took the lives of 193 Dutch citizens. (Photo by Yasin Yagci/Anadolu Agency/Getty Images)