Colour terms in Irish were discussed on this list a long time ago, mainly
with reference to modern Irish. Someone (can't remember who) gave us a
reference (which I followed up) - it is:
RPM Lehmann (University of Texas at Austin): Colour Usage in Irish; in
"Studies in Language, Literature and Culture of the Middle Ages and Later",
edited by E Bagby Atwood and Archibald A Hill. Published by the University
of Texas at Austin, 1969. The art is on pp 73-79.
I see that this article contains a further reference, which it describes as
"a study of colour in Old Irish": Johanna Pollah, Zeitschrift fu"r Celtische
Philologie 27:3/4 pp. 161ff. 1959.
There is a general anthropological book on colour by Berlin and Kay.
Ciara/n O/ Duibhi/n.