What do we learn from the story about the structure of French society at the time the story was written?

In late 19th century France, as elsewhere in Europe, the upper middle class or bourgeoisie constituted a significant segment of society, and constantly confirmed to itself its worth through conspicuous consumption and entertainment. Madame Loisel is representative of the lower stratum that aspired in vain to bourgeois status. The root of Madame Loisel’s problems is her obsession with appearances. Because she wants to seem elegant and wealthier than she is, she borrows the necklace. Her discussion with her husband and her desires for elegance also encompass criticism of her husband for not being wealthy so he could shower her with luxuries.
The descriptions of the things that the materialistic Madame Loisel regrets not having offer a glimpse into the kinds of things that high-status people did have: Oriental tapestries on the walls, large overstuffed armchairs, and the bright light and heat of tall lamps and a big stove. She also dreams of servants to do her bidding, imagining herself overworked and deserving of assistance from not one but two butlers.
Monsieur Loisel’s position as a minor clerk at the Ministry of Public Instruction and his boss’s invitation to a fancy party are also part of the social milieu that the author critiques. During this era, the idea of making education available was gaining currency, and more generally, the number and type of state institutions were growing in France. The minister also wanted to show off his own importance by hosting the party, and Loisel wanted to confirm his worth by attending and showing off his wife, attired in the proper dress and jewels.
The sham and artifice of society is clearly conveyed both by the clichéd character of Madame Loisel’s desires and the misleading behavior of Madame Forestier. She too wanted more than she could have; she too was more concerned with appearances than substance. The irony of the situation, that the Loisels labored to replace something worthless, further confirms de Maupassant’s assessment of the superficiality of the society in which he lived.