WebMD says the best way to hide dark circles is with a cosmetic concealing product...

We found that if you use warm tea bags over the eyes for 15 minutes you arise with lighter and tighter eyes. If you're in a hurry keep a spoon in the freezer at all times and place it over each eye until they feel awakened.

Vitamin K is what helps to clear dark circle. Jello gelatin is high in vitamin K...

Also,
-Get plenty of sleep.
-Eat plenty of fruits and vegetables.
-Drink plenty of water.
-Exercise daily.
-Maintain good hygiene.
-Stay out the sun and use sun block.

Lastly...one we have not tried (because tea bags work great and I have allergies) is Preparation H...