Ring fingers turning blue...

[AustinTink]

... right around the ring. It has happened a couple of times to me, most recently today. They are 14k, so they most likely have copper, or nickel mixed in. But... what the heck causes this?

 

[MomofKatie]

I get this almost every month (right around my "time of the month")- the area of my finger touching gold gets dk blue/black. It easily rubs or washes off, but is really annoying. I was told it has something to do with the acidity of the foods I eat then. IDK, but it only seems to affect me one week a month- maybe it has to do with the different chemical/hormone levels in my skin then??