Here is the quotation that inspired this question:
“The mother's impassioned state had been the medium through which were transmitted to the unborn infant the rays of its moral life; and, however white and clear originally, they had taken the deep stains of crimson and gold, the fiery lustre, the black shadow, and the untempered light, of the intervening substance…”
Pearl, like all children, is born innocent. Yet, this quotation seems to be indicating that, due to the distress of her mother, she has taken on some of her mother’s sin. She has “taken the deep stains of crimson and gold.” These are the colors of the Scarlet Letter, crimson embroidered with gold thread. The “black shadow” could be the mark of sin on her mother’s soul.
The colors also appear later in the chapter. Pearl’s eyes, for example, are black. The narrator tells us that the first object that caught her interest as a baby was
“the scarlet letter on Hester's bosom! One day, as her mother stooped over the cradle, the infant's eyes had been caught by the glimmering of the gold embroidery about the letter; and, putting up her little hand, she grasped at it, smiling, not doubtfully, but with a decided gleam that gave her face the look of a much older child.”
The emotional effects of these colors, then, are as follows: crimson and gold evoke the scarlet letter, or the sin. They also are symbolic of Pearl’s defiance in the face of the children of the town, and of her embodiment as the “living Scarlet Letter.” Black is the color of sin, and where the crimson and gold are bright and defiant, the black represents the sin she has committed and makes the reader feel both sorry for her and wary of her at the same time.