This gown is predominantly seen in Episode I, The Phantom Menace, where it is used on Naboo in the throne room when Queen Amidala first talk with the Trade Federation and her council about the risks of war. Later on it is worn again after Queen Amidala successfully recapture Theed and meet with senator Palpatine.
It is also briefly used in Episode III, Revenge of the Sith, where it appears in the background among the opera goers.