Urb commented on my vypers yesterday and said how the "purplish-blue" riders looked out of place.
Well, yeah, you're absolutely right. That's an older paint scheme that I'm slowly replacing. So here is the full story.
About 15 or so years ago, I started collecting Eldar. I was young and foolish and painted poorly, but the paint scheme I picked was blue and white for vehciles and guardians, and various colours for the aspect warriors.
As I got better and learned the joys of stripping models, I changed my scheme from blue and white to black and red on vehciles and war machines, ivory on heavy weapons, black on personal weapons, and cobalt blue (aka purplish blue) on all guardians. Aspect warriors remained in shrine colours. This odd combination was the scheme for the majority of the years of painting.
Recently, my Eldar got trimmed down and are being rebuilt and repainted. I'm going with the new red and black scheme with ivory coloured weapons WITHOUT exception. War machines, guardians, aspect warriors, psykers, all will follow the same pattern. I love the effect so far and can't wait to have a complete army.
Some painted items like the vypers are close enough to suffice until they can be repainted. Hence the blue guardian driver and gunner.