In "The Necklace," how does Madame Loisel change during the course of the story? What causes her to change?

As a young wife, Madame Loisel is a very pretty young woman married to a clerk, living without wealth or possessions. She is dissatisfied with her drab lot in life, always longing for the beautiful things she does not own and cannot enjoy. When she has an opportunity to attend a glamorous ball with her husband, she buys a gown with money he has carefully saved and borrows a diamond necklace from her childhood friend to wear for her special evening.

After losing the necklace, Madame and her husband keep its loss a secret, borrow money, and replace the missing diamond jewelry. They are then thrust into extreme poverty. For ten years, they both work hard to pay the money they borrowed plus the interest on the loan. Madame Loisel learns to perform hard physical labor of the most menial kind. Her hands become rough; her voice becomes loud and shrill. She ages quickly and loses her beauty. However, her character changes, also. She does not complain. She becomes quite heroic in her efforts to meet her responsibilities.

When she meets her friend after the loan has been repaid, Madame Loisel tells her that the necklace she had returned had been a replacement. Madame Loisel is proud that her friend had never known the difference and that the debt was now paid. She feels quite satisfied with her cleverness--until she learns the diamond necklace she had replaced had been of no particular value, its stones made of paste. With this the story ends. We can only imagine how Madame Loisel must have felt upon hearing this news, remembering how she had spent the last ten years of her life.