The Privilège du Blanc is the honour of wearing a white dress and matching mantilla in the presence of the Pope. This honour is only accorded to certain Catholic monarchs. Normally women are required to wear a long black dress with a high collar and long sleeves, with a black mantilla during an audience with the Pope.
The privilege is only retained at the discretion of the Pope. She must remain a Catholic in good public standing. She may choose to exercise the privilege freely and she is not required to wear white.
Currently, the following women are eligible for the privilege:
HM Queen Sofía of Spain
HM Queen Paola of the Belgians
HRH The Grand Duchess of Luxembourg
HSH The Princess of Monaco
HM The Queen of the Belgians
HM The Queen of Spain
HRH The Princess of Naples
While Queen Maxima of the Netherlands is a Catholic, she is not accorded the privilege because she is married to a non-Catholic.