Violet was hard to find and I had to resort to a close up of a flower. In this particular example I think that the normal exposure is the closest to the purple on the ring.
For orange I chose a wall that contained some very orange bricks, they were used with red brick to make a pattern. Again, I think that that colour that matches the examples is the one without any exposure compensation. The under exposed image looks too drab and the over exposed too washed out.
Again green looks more like the circle in the most under exposed form of a picture of a fig leaf. I took this one because of the lines and curves, does this mean I am learning? It seems that so far all the primary colours look best under exposed!