Quote 4
"It annoys me not to have a jewel, not a single stone, to put on. I shall look wretched. I would almost rather not go to this party." (33)
OK, so after she's gotten an expensive dress out of her husband, Mathilde refuses to go to the party again. She's still not satisfied. This time, it's jewels. She needs jewels. Does this mean Mathilde actually expects her husband to get her a piece of jewelry?
Quote 5
All at once she discovered, in a box of black satin, a superb necklace of diamonds, and her heart began to beat with boundless desire. Her hands trembled in taking it up. She fastened it round her throat, on her high dress, and remained in ecstasy before herself. (48)
Maybe diamonds are a girl's best friend. Just seeing and touching something expensive and beautiful drives Mathilde crazy. She's in "ecstasy" over a necklace. The necklace may be a symbol for wealth, or glamour in the story. Even if it isn't, it certainly seems to equate to those things for Mathilde.
Quote 6
Mme. Loisel learned the horrible life of the needy. She made the best of it, moreover, frankly, heroically. The frightful debt must be paid. She would pay it. They dismissed the servant; they changed their rooms; they took an attic under the roof. (98)
After losing the necklace, Mathilde now finds herself actually poor. Though she felt herself "poor" before, she was fairly comfortable, and middle class. Now her life is much harder.