Undereye circles have pleged me for years, since I remember. According to my cosmetic surgeon (yes I have even consulted one for this), its a cause of thin skin under the eyes which allow the blood vessels to show through. He recommended using AHAVA, Mineral Eye Cream to draw out some of the mosture from the skin in order to shrink and minimize the blood vessels. Just started it, so I don't know if it works, it typically takes 6-8 weeks to see any difference. I also use Keromask Masking Cream as a concealer. Oldly enough, whenever I'm on vacation on the beach, my undereye circles disappear... I think its being in the sun and drying out my skinn that works (I don't tan).
Good Luck, I know its a huge pain in the A#$.
Monika