How did Madame Loisel's new life change her appearance and manner?

With Madame Forestier's sparkling diamonds adorning her pretty neck, Mathilde Loisel feels like a star. She's always thought herself so much better than her lowly petit bourgeois existence would suggest; but now, she feels like a princess as she becomes the center of attention at the Education Ministry ball. Heads turn; she's by far the most beautiful woman there, and all men's eyes are upon her. No less a VIP than the Minister himself notices Mathilde, and all the cabinet officials want to dance with her. She is truly the belle of the ball and the toast of high society. Isn't it amazing what a diamond necklace can do?
Madame Loisel feels that she's now become what she always really was: a lady of the aristocracy. Only, she isn't really. Just as her aristocratic pretensions are fake, so too are the diamonds which so cruelly fan the flames of her delusions of grandeur.
When she subsequently loses the necklace, Madame Loisel is devastated. But somehow she and her husband must pay for a replacement, however much it costs. So they take out huge loans with a number of different creditors, even though they know full well they won't be able to pay them back for many years to come.
After laying down 36,000 francs for a replacement necklace, the Loisels are humiliatingly forced into a drastic change in their lifestyle. They dismiss their maid; they move into a poky little garret; they have no choice but to work their fingers to the bone just to make ends meet. And this goes on for ten long, miserable years. Mathilde and her husband now know what it's like to be very poor.
And this is what's so ironic. In wearing the necklace, Mathilde thought she would rise above her straightened circumstances, to become the princess she always thought she was. Yet now, when Madame Forestier catches up with her after all this time, the physical signs of a decade of grinding poverty are visibly etched all over Mathilde's drawn, haggard features. Instead of going up in the world, Madame Loisel has come crashing down to the very bottom. Although she may have developed all the strength and hardy roughness of the impoverished Parisienne, her new life is still a far cry, not just from her fantasies of gracious living, but also from the simple but perfectly comfortable lifestyle she enjoyed before that fateful night at the Education Ministry ball.