It seems that everybody sees chakras (active ones). Everybody just isn't aware of it. A chakra that is active radiates light which attracts the eye. A chakra that is active also radiates emotion. This is why everybody can also feel what chakras are active in another person. You know how different people have a different feel to them. If you observe where your eyes are naturally attracted to and what you feel while you're looking at a person you can determine what chakras are active in that person. The more awake you are the easier it is. But it's good to understand that this seeing of chakras and auras seems to be going on all the time whether we are aware of it or not. There is a reason why celebrities are celebrities They are very attractive because they are very radiant. If you want to learn seeing auras and chakras look at the photos of celebrities or spiritual masters.

I've never really focused on developing this ability, it has become more and more active as a side effect of my meditation practice. I may occasionally meditate people's photos just to see what they radiate or when I meditate with my wife we sometimes play the chakra game, where other tries to see/feel what the other is activating. If you can blend your spirit with other person's spirit it's quite easy to know what the other person is doing.

I believe yes, chakras can/are seen.  As a Reiki practioner I feel or see the chakras or the vibrations dependent upon the circumstances.  I don't think I learned how to see, I think I allowed the natrual-ness of the seeing to come forward.