what is the theme of the story

There are a number of themes that you can consider. I think that wealth is an important one. The expensive piece of jewelry, the necklace, drives the story's plot. Mathilde fantasizes that this necklace will make her look rich and desirable to the affluent people at the ball. Mathilde becomes even more obsessed with wealth after she sees the necklace. After loosing the necklace Mathilde begins to understand that happiness and wealth are not always linked.