Colored contacts are professionally tinted by people that create the contact lenses. Under no circumstances should you ever attempt to dye colored contacts on your own. There are many dangerous factors to tinting colored contacts yourself. The biggest factor being that you can permanently damage your eyes and make yourself go blind.

Certain chemicals that could be used to dye the contacts can reverse the contours of the lenses and make them scratch your eyeball. This would be very painful and could end up leading to your needing surgery. Even food dyes that are okay to use in the dying of clothing and hair can be damaging to your eye because you are introducing an unknown substance to your eye that your body is immediately going to try and reject. Find out more about colored contact lenses through the link.