Octarine

Well, The Colour of Magic describes it as

I think i am going to be unimaginative and stick with that.:wink:

 

I think in the text, Rincewind describes it as a sort of greenish-purple. Given that it's the 'eighth color' and, i think in Jingo it's described as being beyond Violet in the spectrum, i'm inclined to assume it's a sort of reddish purple.

 

I always imagined it as described in the text Hsing quoted.