Princess Caroline of Monaco wore a modified version of a black and silver Fall 2011 Chanel gown. The dress features a diamond shaped opening in the back. This was worn on the evening of the civil wedding service at the gala dinner hosted by the Grand Ducal Couple.

She carried a black clutch and wore a pair of black glitter Christian Louboutin heels. Princess Caroline also wore the platinum and white gold Cartier Tiara. She wore other jewels belonging to Monaco's Princely Family, as well: the Art Deco earrings and the Diamond Fringe necklace (both of which used to belong to her paternal grandmother).

Celebrations took place over a two day period in Luxembourg. The civil service between Prince  Guillaume, Hereditary Grand Duke of Luxembourg and Countess Stéphanie de Lannoy took place on October 19, 2012. The religious ceremony took place the next day at Notre-Dame Cathedral in Luxembourg City. 

Royals from all over the world were in the small, landlocked European country for the festivities. Besides Princess Caroline, others who attended included Queen Fabiola, King Albert, Queen Paola, then-Prince Philippe and then-Princess Mathilde of Belgium; Queen Margrethe, Prince Henrik, Crown Prince Frederik and Crown Princess Mary of Denmark; King Constantine, Queen Anne-Marie, Crown Prince Pavlos and Crown Princess Marie-Chantal of Greece; Queen Silvia, Crown Princess Victoria, Prince Daniel and Prince Carl Philip of Sweden; and Crown Prince Naruhito of Japan. 

The vast majority of monarchies, both current and former, were represented. As you can imagine, listing them all would make this quite a long piece.