The fact that she uses the tents of nomads as a comparison maybe affirms her self-consciousness of what the colour of skin says about her status.
In contrast, the curtains of Solomon, probably in his palace, would have been beautiful and spoke of great nobility. So, as aware as she is of her dark skin, she is able to acknowledge her beauty.
5 I am very dark, but lovely, O daughters of Jerusalem, like the tents of Kedar, like the curtains of Solomon.