Because of Hester's natural ability at the needle, she uses it by lavishing outrageous garments on little Pearl. These clothes went entirely against the Puritan tenet of austerity and the vow of poverty and humbleness that makes them stand out. Pearl dresses in vivid colors, using shiny silks and with outrageous patterns all the time. Her flamboyant clothes, combined with her wild personality, make her stand out from everyone. Among many other descriptors, Hawthorne compares Pearl to an exotic bird.

However, in chapter 7, Hester dresses up Pearl with a very unique robe. 

A crimson velvet tunic, of a peculiar cut, abundantly embroidered with fantasies and flourishes of gold thread.

After the raucous behavior that Pearl displays at the mansion, the things that she says to the people, and the awkward nature of her demeanor, it is clear that this child is there to remind to her mother forever of her sins. In the past, the little girl has mocked her mother, disobeyed her, kept her from sleep, and she continuously makes a point to remind her of the scarlet letter. Ironically, in her conversation with the governor, Hester claims that the letter is like Pearl in that they have both taught her many lessons. This is when Hawthorne makes what is perhaps one of the most interesting statements about Pearl,

It was the scarlet letter in another form; the scarlet letter endowed with life!

Theerefore, Hawthorne believes that Pearl is Hester's sin, living and breathing, reminding her forever (like a curse) of what she has done.

What is the significance of Pearl's clothing in The Scarlet Letter?

In the chapter entitled "Pearl," the narrator makes a particular point of talking about the way in which Hester dressed her daughter. What is so interesting about this is the way that there is a deliberate link made between the scarlet letter that Hester wears on her breast, that the reader is told is so lavishly and beautifully sewn on, and the way that Pearl, the fruit of that illicit adulterous union, is presented:

Her mother, with a morbid purpose that may be better understood hereafter, had bought the richest tissues that could be procured, and allowed her imaginative faculty its full play in the arrangement and decoration of the dresses which the child wore before the public eye.

Just as the scarlet "A" that Hester is forced to wear is turned by her skill with the needle into a symbol of beauty and finery, so Pearl, the illegitimate child of an illicit and unlawful union, is a figure of beauty and is arrayed in all finery by her mother. Far from being ashamed of her state and of her daughter, Hester Prynne seems almost to flaunt her in front of the society that has made her an outcast and branded both her and her daughter sinners. One way of viewing the appearance of Pearl therefore is to consider the way in which Hester Prynne subtlely challenges and subverts the rules and beliefs of the day through turning what is despised into things of beauty and value.