Tomato paste is one of the most effective remedies for dark circles. You can make it easily at home.
one or two fresh tomatoes,
one tablespoon of lemon juice
and a pinch of gram flour and turmeric powder.
Blend these ingredients nicely until they become a thick paste and apply it very gently around your eyes. Rinse it off gently with clean water after 10 or 20 minutes.
Repeating this process twice or thrice every week will make your skin tone around your eyes lighter and will eventually make your dark circles go away completely.