How atractive do you think is to have different hair colors? Is this healthy for a 14 year old?

Not up to me. Different people think different hair colors are attractive. What do you think? I personally do not like a lot of chemicals in the hair as some may be absorbed through the scalp. If you feel the need to experiment, use colors that washout easily. Do some research and see what is in the products you want to use. And you will probably need permission/assistance from your parents.
Rainbow. Chemicals are not usually good for your hair or scalp.However the important question is what do you think, and what do your parents think..If it makes you feel good, and your parents allow it go for it.