Franklin Blake meets Ezra Jennings, who is described as having a strange face and piebald hair, or hair of different colors all over the head. His first impression is not positive, but he finds himself oddly drawn to Jennings, not only for the information that he has but because Jennings seems to be entirely without friends, and seen in a negative way simply for his appearance. As it turns out, Jennings has his odd appearence because of a disease, which eventually kills him, and Blake, after conversation, comes to the following conclusion:

The little that he had said, thus far, had been sufficient to convince me that I was speaking to a gentleman. He had what I may venture to describe as the UNSOUGHT SELF-POSSESSION, which is a sure sign of good breeding...
(Collins, The Moonstone, gutenberg.org)

In other words, Blake has come to the conclusion that a person's outward appearance does not definitely correlate to his inward personality. This is probably an attempt at diversity in early literature, and could also have been a direct stab by author Wilkie Collins at Charles Dickens, who often used outward appearance to show a character's inner personality. Either way, Jennings is made more of a reputable character through Blake's opinion.