That's what I figured. I was showing the game to a friend that I did not know was colorblind, and while he can distinguish between various tints, the tints of some hues look identical. I tried to show him what clay was on the worldmap, and he could not tell where the light green stopped and the grey/blue began, even when I took a screenshot and zoomed in until there were only a handful of the map pixels on the screen.
I tried tweaking some of the .pngs and found that was not the answer. I could change the color of the clay forming, not the map color or the block color. And I could not find where that node color was defined.