The next section of the story features the much-anticipated ball at the Ministry of Public Instruction. Mathilde and Loisel arrive at the ball and Mathilde, in her fine new dress and borrowed jewels, is the prettiest woman there. She is a true picture of elegance, extravagance, class, and grace. All of the men at the party are enamored by her beauty and wish to be introduced to her or dance with her. She dances the whole night as Loisel dozes in the corner. Mathilde feels fiercely proud, triumphant, and victorious, and is overjoyed by the attention she draws. The night comes to a close at roughly 4 o'clock in the morning and as they prepare to depart, Loisel wraps Mathilde in a modest shawl. The shawl contrasts with her elegant appearance and Mathilde, who observes other party guests don their fur coats, is embarrassed by the ordinary garment. Displeased, she wishes to "escape" the wrap and ventures outside without the shawl.
The couple departs and goes outside to find a cab. They make their way toward the Seine and eventually find a cab that brings them home. Mathilde is devastated that her magical evening has come to an end. Once they arrive home, she admires her reflection once more. However, as she gazes at herself in the mirror, she realizes in shock that the diamond necklace is gone. Mathilde and Loisel search for the necklace but are unable to find it. Loisel then retraces their steps in a desperate attempt to locate the jewels but comes back home empty-handed. The following day, he goes to the police, offers a reward in the newspaper, and contacts the local cab companies. Despite his efforts, there is no sign of the necklace. To buy them some time, he instructs Mathilde to tell Madame Forestier that she is mending a broken clasp on the necklace and that she will return the jewels soon. However, by the week's end, they still have not found the necklace. As a last resort, they elect to purchase a replacement necklace so that Madame Forestier will never learn of the missing jewels. Mathilde and Loisel try to track down the original jeweler, to no avail, and finally find a diamond necklace at the Palais Royal that seems an exact likeness to the original. An extravagant piece of jewelry, the necklace costs 40,000 francs, though Mathilde and Monsieur Loisel bargain the price down to 36,000 francs. After using all of their savings as well as taking out additional loans, the couple desperately comes up with the money. Loisel knows that this will cost him great misfortune and prove to be an immense burden for the rest of their lives. However, they move forward with their plan and buy the necklace. Mathilde brings this fake necklace to Madame Forestier, who does not notice a difference and is displeased that Mathilde did not return it sooner.