This drawing of 'Golden Eye' by Daria Dzyuba is amazing! He has just used 4 colours (dark yellow, light brown, dark brown and black) and HB mechanical pencil. For the brightness of the eye he has used a rubber and white gouache.
I have an obsession with eyes. I do believe that they are the windows to the soul. I draw eyes in a lot of my notebooks and on almost all of my school work. I find them so. I hope you like this awesome pic of a lot of this colorful eye :)