One of the central themes of "The Necklace" is that of appearance vs. reality. For Mathilde, the necklace symbolizes wealth, beauty, and, ultimately, shame, as she loses the necklace and goes into debt to replace it. The great irony of the story is that the necklace was a fake. Mathilde spends ten years in debt, effectively ruining her life over nothing.
The theme of the short story, "The Necklace" is to be happy with who you are and what you have. Madame Loisel lived in the middle class society but longed to be a member of high society. She wanted to live above her means and would do whatever it took to get there. Her husband provided the stepping stone to enter the world of the upper class by getting an invitation to a prominent reception. From there she talked her husband into giving her the money to have a wonderful dress to fit in with them and then the final highlight was to borrow a wonderful diamond necklace from Madame Forestier to wear to the reception. The ironic situation is the source of her joy, the necklace, becomes her downfall when she loses it and has to work the next ten years of her life to replace it. She not only loses her middle income status but falls into poverty and spends the rest of her life suffering for her dreams. The symbolism of the necklace is social acceptance into a world where she longs to be, but doesn't belong.
The main themes of “The Necklace” first and foremost, in my opinion, is Class Conflict as Madame Loisel, a member of lower class strives to appear to be in a higher class than she actually is, which causes conflict, but it also hints at another theme of Appearances and Reality. Madame Loisel is determined to make herself appear to be at a higher level on the social ladder than she actually is; however her desire to attain this goal leads to a display of Generosity on the part of Madame Forestier as she loans a very expensive necklace to the Greedy Madame Loisel who looses it. The necklace actually seems to be a symbol of her life, the insincerity of her character, and how her greed leads to her ultimate misery in life because she is forced to give up her own goals in life to repay Madame Forestier for the necklace she has lost, effectively ending her feeble climb up the social ladder. Irony is best demonstrated in the fact that she wastes her life to pay for a cheap copy of the original necklace, while she herself is nothing more than a cheap copy. Check the links below for more information.
Enotes has an excellent response to your question at the URL below. The necklace itself represents the theme of appearances versus reality. “While sufficiently beautiful to make Madame Loisel feel comfortable during the ministerial ball, the necklace is actually nothing more than paste and gilt. Thus, it is not the reality of wealth or high social class that is important for Madame Loisel, just the appearance of it.” As the discussion on enotes points out, other themes involve conflict of class (rich vs poor) and greed and generosity. The irony in the story is that Madame Loisel ruins her life in trying to compensate for the lost necklace, when in fact the necklace was not worth anything to begin with. As for symbolism, it resides in the title which also carries the theme: the necklace symbolizes the difference between appearance of and reality, a wealth that is empty, having no real value.
The Necklace's theme is to be happy of what you have now, and treasure it. Like Madame Loisel, she thinks that she didn't have enough after buying the beautiful dress using his husband's 400 francs, she borrowed her friend's daimond necklace. If she knew to treasure what she have, the daimond necklac ewon't be lost and she would not need to spend 10 years working for the money for the daimond necklace. Actually, in my opinion I think Madame Loisel did not only trouble herself but also her husband, her husband had to work with her for 10 years to earn back the money.
Usually, after 10 years, there will be a lot of money if they svae their money, but in order to pay back the necklace, they had to . This made them face poverty.
There isn't a single theme to "The Necklace", but I think one of the main themes is that rich people are often idealized in society. Basically this means that if you're poor or middle class, often times you think rich people have all they could want and can buy anything they want.
This theme is illustrated in the story directly through symbolism, and is also connected to situational irony. Because Madame Loisel assumes that her rich friend's necklace is made of real gems, it shows she idealizes the rich class and considers them to be happy and perfect. She longs to be just like them, and believes adamantly that being middle class is shameful: "She suffered endlesslessly, feeling herself born for every delicacy and luxury". Madame Loisel is not satisfied with her physical beauty alone, but yearns for wealth and extravagance. This shous her frivolous attitude and how she considers money more important than anything. She is potrayed as materialistic and relies only on the appearance - which later in the story is the cause of her fall into poverty.