How is The Necklace an example of economic determinism?
In addition to the excellent answer above, Mathilde in "The Necklace" is trapped in her situation. If you think of her as an artist, for instance, she cannot afford the "beauty" around her that an artist craves. As an uneducated poor woman, there is not much she can do about it. The story demonstrates what drastic steps she has to take when she does really need money after she loses the necklace.
Plus, her economic situation somewhat leads to her fall: only a poor person who had never owned much jewelry would have been totally ignorant of the fact that the jewelry might be costume jewelry. Her friend who loans her the necklace certainly would have considered the possibility.
This story raises the issue of poverty and certainly could be viewed as an example of fiction that treats economic determinism. Of course, being poor is not the only obstacle Mathilde has to contend with. She's also a woman in a patriarchy.
The short story 'The Necklace' by Guy de Maupassant also raises the thorny question of debt and it's relation to the economic dynamics not only of a country and a family but also for an individual or a couple on only one salary. When you think about it, the couple could not see how 'rich' they were in terms of economic peace of mind and lack of shackles of debt. The wife unfortunately, like many of us, can only look back at this freedom in hindsight (a true case of 'you don't know what you've got til it's gone.) They had a roof over their head, food, clothes, and crucially - a job which represented the future and the means to climbing up the ladder of progress and betterment. The Madame unfortunately compared her lot with that of the wrong people and found it wanting and shabby - she should have compared to the economic lot of those lower down.
Maupassant introduces the idea of "the horrible life of the needy" in paragraph 98, and his description of what happens to Mathilde under these circumstances may be construed as an illustration of economic determinism. In addition, the fact that Jeanne Forrestier is "always youthful, always beautiful, always attractive" can be read the same way inasmuch as Jeanne is "rich" (paragraph 6). The clear contrast, together with Maupassant’s paragraph about "What would life have been like if she had not lost that necklace?" (paragraph 105), indicates that in this story at least Maupassant makes a connection between the economic condition of people and their happiness and character fulfillment.