This is a very interesting thread. I never had any symptom like this before...until...I was camping and played a djembe drum most of the night through a number of drum circles. I played far too long, got blisters and swolen fingers and hands. Ever since that time both index fingers have experienced this odd sensation of being cold. They both get fact quite cold to the touch compared to other fingers. Tried the finger nail pressure test mentioned early on in this thread and the nails both turn back to a normal pink color as quickly as others...but they are indeed quite cold...! ???