Ancient Sumerians used lapis lazuli rather often and ancient Greek mosaics used blue tiles consistently (in that they don't use blue and green interchangeably, they don't mix blue and other colors for which they lacked distinct terminology). I think the difference in terminology just has to do with different systems of categorizing the same colors. Here's a good paper that responds specifically to the Himba experiment and that I think is on the right track: http://www.linguistics.ucla.edu/people/schuh/lx001/Discussion/d01_Himba_color_perception_critique.pdf As far as the green squares go, I successfully identified the tile that is a different shade but I certainly don't have a separate word to describe that square. I can't even come up with a good way to distinguish it from the other squares using words. It just looks slightly different.