What does the necklace represent to Madame Loisel?
For Madame Loisel, the necklace represents an entree into a lifestyle to which she believes herself fully entitled. Though living a fairly ordinary, lower-middle-class life, she has delusions of grandeur, believing herself to be of noble origin.
Wearing what she thinks is a valuable necklace allows Mathilde to live her dreams, to act out her long-held fantasies of being an aristocratic lady, mixing with the cream of high society. When she puts on that necklace, the dream suddenly becomes real: the women admire her extraordinary beauty and all the men want to dance with her. Mathilde is the center of attention, which is nothing more than her due, as far as she's concerned.
The necklace also represents hope: hope for a better life; hope for a more socially elevated future; hope for Mathilde to be recognized and respected as the high-born lady of quality whom she's always believed herself to be.
Madame Mathilde Loisel's borrowed necklace symbolizes the dream that she has always desired: "to be envied, to be charming, to be sought after." For one night at the ball, Madame Loisel will be that person.
Madame Loisel was a great success. She was prettier than any other woman present, elegant, graceful, smiling and wild with joy. All the men looked at her, asked her name, sought to be introduced.
Without the necklace, the dress would not have sufficed. Without the dress, she would not have been attired properly. The necklace was the final piece of the puzzle to make her the belle of the ball--at least for one night.
After the necklace was lost, it came to represent the greatest folly of her life: She traded everything for the one night, and when she lost the necklace, she and her husband spent the next decade repaying the debts it encountered.