Gopalacampu 1.6.56

1.6.56

[43] athānujam uddiśya,
"śuklo raktaḥ pīta ity ādi-varṇās
tat-tad-bhāvād asya tat-tad-yugeṣu |
tat-tan-mūla-śyāmataikātmya-yogāj
janmany asmin kṛṣṇa-nāmāyam asti || [śālinī]

[43] Then, with reference to the younger brother:
"White, red, yellow, and so forth are his colors / in various ages according to his various moods; / because in this birth he is united with the essential dark complexion that is the source of them all, / he is named Kṛṣṇa." [JGc 1.6.32]