Blue or Green?

Blue or Green?
2005.11.08 2:18

One of my favourite cheese is Gorgonzola - one of the blue cheese family, but actually there's no blue part in its body, but green mold. We call cheese with green mold blue cheese, we call green blue.
One of my colleages asked me to bring a blue paper. I was unable to find the one, but it turned to be a green paper.
We call green signal blue. What difference makes us call blue instead of green in many cases? Are some people only perceive blue in green object?