Gjestvang won the award for a portrait series she created called 'One Day in History', chronicling the survivors of the 2011 Utoeya massacre. Speaking of Gjestvang's work, chairman of the jury Catherine Chermayeff said:
“As the Jury Chairman I am delighted that Andrea Gjestvang has won the L'Iris d'Or prize. The entire jury was unanimous in selecting this body of work. "One Day in History" is a quiet, thoughtful and ultimately powerful voice for the children and survivors of the massacre in Norway. We were all moved by the dignity and beauty of these images.”
The winning series, alongside other winners in the competition, will be shown at the 2013 Sony World Photography Awards Exhibition at Somerset House, and published in the 2013 edition of the Sony World Photography Awards book.