What is the plot of the short story 'The Diamond Necklace'?

There are two different stories- the Affair of the Diamond Necklace is about the period of Marie Antoinette. the Necklace by Guy de Maupassant is a moralistic short story about a ( social climbing) stunt that fails went he title property is lost- it is not stated specifically HOW it is lost. Victim is so drunk with pride she does NOT immediately report the loss to the owner, MMe Forestier- well the downhill slide starts. I don"t think it could happen in real life.