Madame Forestier is a character from the short story "The Necklace" by Guy de Maupassant. She is a wealthy friend of Mathilde Loisel, the protagonist, who borrows a beautiful diamond necklace from her for a fancy event. Madame Forestier is depicted as kind and generous, unaware of the struggles that Mathilde faces. After losing the necklace, Mathilde and her husband endure years of hardship to repay the debt. Eventually, Mathilde encounters Madame Forestier again and learns that the original necklace was a fake. This revelation highlights themes of pride, appearance, and the consequences of one's choices.