my labias are black and one of them is a lot bigger/longer than the other :S

Hi! A chronic purple color could be caused by a yeast infection or chronic irritation of the vulva, known as Lichen Simplex. A yeast infection frequently changes the vulva from a pale pink to a red, although not necessarily purple. You can check out what is bacterial vaginosis to see if any signs or symptoms related to a vaginal yeast infection are present. As for the size of you labia, there's nothing to worry about. Trying to define "normal" for labia is sort of like trying to define normal hairstyles. But if you truly think something is abnormal or seriously problematic, talk to your gynecologist.