A: Alvor has a custom lip color. For console users, the closest match is the default 0.
H: Lord Harkon has a custom eye color. If you're on PS3 or XBOX 360, you'll have to choose a different color.
K: Karliah has a custom eye color not available to players. If you're on PS3 or XBOX 360, you'll have to choose a different eye color. If you're on PC, you can download the Karliah plugin to access her custom eye color.
N: Nocturnal uses a custom skin texture. If you're on PS3 or XBOX 360, you may want to use the Nord race instead and choose the lightest Skin Tone. If you're on PC, you can download my Nocturnal plugin to access the custom color.
S: Serana has custom hair and eyes, and several custom skin tone settings. If you're on PS3 or XBOX 360, you'll have to choose different settings. Custom settings are included with the PC download.