The most important thing about Jonas’s appearance is his eyes. Jonas’s eyes separate him from the rest of the community, and seem to genetically predispose him to the “gift” of Capacity to See Beyond.
Jonas has pale eyes, when everyone else’s are dark. There are few people with pale eyes: Gabriel, The Giver, and a female Five.
No one mentioned such things; it was not a rule, but was considered rude to call attention to things that were unsettling or different about individuals. (ch 3, p. 20)
Jonas looks like everyone else in most other senses. He has brown hair, and it is cut short (everyone has the same haircut, based on age).
Jonas is white. We know that there used to be different skin tones, but they eliminated them when they chose Sameness.
Today flesh is all the same, and what you saw was the red tones. Probably when you saw the faces take on color it wasn't as deep or vibrant as the apple… (ch 13, pp. 94-95)
Jonas wears a tunic, which is kind of like a long shirt, and pants. He dresses like everyone else.
Jonas's eyes are significant because they separate him from the others. Even though it's not polite to talk about his eyes, it is clear that Jonas has always been a little different.
Lowry, Lois (1993-04-26). The Giver (Newbery Medal Book). Houghton Mifflin Harcourt. Kindle Edition.