Finally, the word "varna" also means "color". I am currently searching the rik in the RgVeda that I remember mentions all the six different colors of DyavaPrithvi in the context of Agni. In my next post, and hopefully the last in this thread, I will present that rik.
RV 10.20.09
देवता/ अग्निः
कृष्णः श्वेतोऽरुषो यामो अस्य ब्रध्न ऋज्र उत शोणो यशस्वान् । हिरण्यरूपं जनिता जजान ॥
"Dark", "silvery (white)", "brilliant (like rising sun)" is this way of his like; and glorious "light brown", "reddish", "fiery yellow". His bringer (Matarisvan) created him (Agni) golden hued (sum of all?).

In the context of Varna, arguably, this can mean:

Varna------- Color ---------------- Gods
ShUdra: light brown & dark: Marut & Bhag
Kshatra: reddish & silvery: Mitra & Varuna
Brahman: yellow & brilliant: Indra & Vayu