Dark circles can be caused by lack of sleep, prolonged sun exposure, an unbalanced diet, or stress. However, it seems that the main cause is heredity. You should know that there is no treatment that can help you get rid of dark circles for good. However, you have certain simple skin care natural remedies that are also very useful for diminishing under eye dark circles. You have to keep in mind that the effects are not visible immediately, but only in time. Pay a lot of attention what you apply on the area around the eyes as this is a very sensitive skin and any inappropriate substance can be harmful. 
Cucumbers
Cucumbers contain antioxidants, such as phenolic and peroxidase that stimulate blood circulation. They also contain vitamin K that increases the production of proteins and stimulates circulation. Therefore, they are very helpful in fighting against dark circles, but only temporary. Place a cucumber in the fridge for about 5 to 10 minutes. Cut two slices and apply them on your eyes for 10 minutes. You can do this both in the morning and in the evening too. You can also make a cucumber juice, dip cotton pads in it and then apply them on your eyes.
Potato juice
Potato juice contains substances that have the amazing property of illuminating the skin affected by dark circles. Therefore, you just have to dip two cotton pads into the potato juice, place them on your eyes, and leave them act for about 20 minutes. An old-fashioned method that seems to work.
Cornflower water
Cornflower water contains two substances that have anti-inflammatory, astringent, and decongestant properties and can help you fight against dark circles, but also for tired and puffy eyes. You can find it in a perfumery or a drugstore. You can even prepare it yourself at home by adding a handful of cornflower in 25 cl boiling water for 10 minutes, then leave it cool. Apply it once a day by soaking cotton pads into it and place them on your eyes for a few minutes.
Powder milk and honey
You can also make a mask using one teaspoon powder milk and one teaspoon honey. Apply the mixture on the dark circles and leave it act for about 15 to 20 minutes. Natural and safe.
Tea
If you apply regularly a tea bag on the eyelids, you will notice how this can help you fight dark circles and fatigue signs around your eyes. The antioxidants in the tea leaves encourage blood circulation including in the most fine vessels of the face. What you can do is put some used tea bags in the fridge for 5 to 10 minutes, then apply them on your eyes. You need to make this quite often as the effect is only temporary.
Ice cubes
The coolness and freshness of the ice cubes stimulate blood circulation around the eyes. Therefore, tissues are cleared for a short period of time. Put the ice cubes in a facecloth avoiding the direct contact with your eyes as this is too aggressive. Keep it on the eyes for about 10 minutes.
Besides these natural remedies, you also have to start realizing how important is sleep for the body recovery. Moreover, you should drink at least 2 l of water daily in order to keep your skin perfectly hydrated, and pay attention to your diet as foods rich in iron are your number one ally against dark circles. Dairy products, fresh fruits and vegetables are the ones you need to consider.