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.