What insight about life is suggested by the contrast between her beautiful dress and the "plain" wraps of her everday life?
The lesson we learn from the contrast of clothes is that it is better to be happy with what you have than unhappy because of what you don’t have.
Madame Loisel wants nothing more than to be wealthy and popular. She was pretty, but not rich.
The girl was one of those pretty and charming young creatures who sometimes are born, as if by a slip of fate, into a family of clerks.
The lesson in “The Necklace” is that pride and envy can destroy you. From the beginning, Mathilde is described as wanting more than she has.
She dressed plainly because she could not dress well, but she was unhappy as if she had really fallen from a higher station; since with women there is neither caste nor rank, for beauty, grace and charm take the place of family and birth.
When she dresses for the party, she is getting a taste of the life she never had but always wanted. She looks radiant, because beauty is one benefit she does have. However, since the necklace symbolizes her pride, the party turns out to be her downfall.