In the beginning of the story, Mathilde evaluates her life and is unhappy and ungrateful for all she has. She felt that her life was provential and lacking the fine things life has to offer.
Her husband came home with an invitation to a ball, he expected her to be happy about this but instead this upset her. She didn't have anything to wear but with 400 francs, that problem was fixed. This shows that she was ungrateful for the invitation and and was selfish for only thinking of what she didn't have, instead of what she had just received.
After being upset about going to the ball again, she went to ask her friend for a necklace, she found one she loved and was very anxious to wear it, this shows that she was being a little greedy and feeling very deprived of what she had not previously been in possession of.
" Why, my necklace was paste. It was worth at most five hundred francs!"
At the ball, Mathilde was having a wonderful time and was very happy, she finally was grateful for the life she had been given. This was her dream come true.
After losing the necklace she replaced it with another simalar necklace to return to her friend, but to buy that necklace they had to use their savings and take loans which kept them in debt for many years. This experience humbled Mathilde and she realized how lucky she had been. This is when she really began to change her perspective of things.
Mathilde was full of guilt, so when she was with her friend again, she explained how she had lied to her and how this lie has made her life miserable these last few years. Her friend then explains that the necklace was fake all along, this showed how Mathilde had a change of heart and was different from in the beginning of the story. Her character became humble and honest.