Color vision

Well first I learned that there is many different forms of color blind. I always thought there was just one form of it where you saw everything as shades of gray. The second thing i learned is that the main colors that color blind people can not see are green, red, orange, brown, pink, and light blue, I just thought that they could not see any color at all. The last big thing that i learned is that they are producing glasses that will let these people see these colors again. This is a huge innovation in the scientific world. To be able to give someone the gift of seeing color again is amazing. Personalty i was thinking of saving up and buying my uncle Billy a pair because i know he is color blind and it does affect his life from time to time. I am just wondering how these glasses exactly work?