The Compendium of Caraka 4.8.15_1

4.8.15_1

api tu tejodhāturapyudakāntarikṣadhātuprāyo'avadātavarṇakaro bhavati, pṛthivīvāyudhātuprāyaḥ kṛṣṇavarṇakaraḥ, samasarvadhātuprāyaḥ śyāmavarṇakaraḥ//

Rather, the fire element also, when dominated by the water and ether elements, produces a fair complexion; when dominated by the earth and wind elements, it produces a dark complexion; and when all elements are equal, it produces a tawny complexion.