Although Aylmer, Georgiana's scientist husband, believes that Georgiana's birthmark--a tiny mark on her cheek in the shape of a hand--represents her "liability to sin, sorrow, decay, and death," Hawthorne tells us that it "would be as reasonable to say" that a small blue streak in perfectly white marble would somehow make the marble horrible--in other words, in Hawthorne's view, the birthmark is has no effect on Georgiana's physical beauty.
The important question, though, is whether the birthmark represents an imperfection in Georgiana's nature--does the mark indicate Georgiana's "liability to sin"? The fact is, there is nothing in the story that casts any doubts on Georgiana's essential goodness and love for Aylmer. In fact, she loves Aylmer so intently that she begins to identify with his hatred of the birthmark:
Danger is nothing to me; for life, while this hateful mark makes me the object of your horror and disgust,--life is a burden which I would fling down with joy.
In other words, Georgiana's love for Aylmer has managed to convert her to Aylmer's obsessive hatred of the birthmark, and she is willing to risk death in order to rid herself of nature's work in order to please her husband.
From a 21stC. perspective, of course, one can always argue that Georgiana's personality was inherently weak and that she should have recognized the obsession of her husband as a destructive menal illness, but that view imparts a modern sensibility to the 19thC. that did not exist at the time. A woman such as Georgiana, bound by societal norms of the time, would have looked to her husband for guidance in most, if not all, matters.
From start to finish, Hawthorne depicts no imperfection in Georgiana other than the physical manifestation of nature's hand in Georgiana's creation, which is only an imperfection in the eyes of a very few people. Her conduct, her love for Aylmer, her trust in Aylmer's skill are all that one could expect of a loving wife at any time, and so the belief in Georgiana's imperfection must be limited to Aylmer, not to the world at large.