In the story Madame Loisel goes to a ball she doesn't normally go to things like these because she is not very rich but she was invited to this event so she decided to go. She buys a fancy dress and borrows a pretty necklace from a rich friend and goes to the ball. A lot of people are amazed on how she looks and thinks she is super rich because of what she is wearing, they all simply judge her on how she looks.
Madame Loisel shows up to the ball looking fancy and pretty on page 3 it says this, “The day of the ball arrived and Madame Loisel had great success she looked prettier then all the women there”. Madame Loisel wasn't actually pretty and rich