Themes in The Necklace
The deep embarrassment they feel at having failed provides insight into their rationale for not admitting that the necklace was lost in the first place. Despite the friendship that Mathilde has with Madame Forestier, it appears that social obligations and class divisions run so deep in society that they would rather make themselves sick trying to solve the problem instead of admitting their mistake.
Mathilde's desire for a new dress and jewelry further characterize her as greedy. This moment where she covetously looks at the diamond necklace provides further support for this characterization, and her greed stands in contrast to the generosity of both her husband and Madame Forestier.
Even though she does not have a lot of money, this desire for material possessions characterizes Mathilde as greedy and runs through the poem as a theme. Throughout the story, Maupassant includes specific details that reinforce this notion, specifically ones that contrast other character's generosity with Mathilde's greed.