X-Rite has posted an Online Color Challenge to test how well people see color.
I thought I did pretty well on this test. My final score was a 98. Turns out a perfect score is 0 and a 99 is 'low color acuity.' How could this be? I thought I had put the colors in the correct order. The highest score for my gender and age was 109748, so at least I wasn't that bad.
Try it and let me know your score.