Royal gowns on display at Kensington Palace

Dresses worn by Princess Diana are displayed at the "Fashion Rules" exhibition at Kensington Palace in London on July 1, 2013.

Opening on July 4, the exhibit showcases how the styles of three royal ladies -- Queen Elizabeth II, her sometimes risque sister, Margaret, and the glamorous Princess Diana -- each reflected and influenced the trends of their fashion heyday.

An employee fixes a dress worn by Queen Elizabeth II on display at the "Fashion Rules" exhibition at Kensington Palace in London on July 1, 2013.

An employee cleans the glass cabinet displaying dresses worn by Queen Elizabeth II at the "Fashion Rules" exhibition at Kensington Palace in London on July 1, 2013.

An employee cleans the glass cabinet showing a turban and dress worn by Princess Margaret at the "Fashion Rules" exhibition at Kensington Palace in London on July 1, 2013.

An employee fixes a dress worn by Princess Margaret to a film premier in London and to a dinner in Paris as a guest of Prince Paul of Yugoslavia in 1951 at the "Fashion Rules" exhibition at Kensington Palace in London on July 1, 2013.

Dresses worn by Princess Diana are displayed at the "Fashion Rules" exhibition at Kensington Palace in London on July 1, 2013.

A caftan and turban, designed by Carl Toms and worn by Princess Margaret, is displayed in the "Fashion Rules" exhibition at Kensington Palace on July 3, 2013, in London.

An evening gown, designed by Norman Hartnell and once worn by Queen Elizabeth II, is displayed in the "Fashion Rules" exhibition at Kensington Palace on July 3, 2013, in London.

Costumes ranging from summer dresses to formal wear are displayed in the "Fashion Rules" exhibition at Kensington Palace on July 3, 2013, in London.