Cersei is very beautiful.She has the typical golden curly hair and green eyes of the Lannister family, and is slender and fair-skinned.Even so, the experience of giving birth to three children left traces of time on her.“The light of the torch cannot be compared with the rising sun.” - Kevan Lannister comments comparing the looks of Lyanna Stark and Cersei.
In terms of personality and appearance, Cersei and Jaime look very similar, like sculptures carved from the same mold.As children, they even swapped clothes and pretended to be each other for a whole day, so even their father, Tywin, couldn't tell.