This thread might be relevant:http://www.network54.com/Forum/244184/message/1327531471/Purple+corona
That is not my thread, but I have the same thing. I posted some images of my darling penis in that thread but they have been removed by the imagehost. I found this picture on google (it is not of me) which looks somewhat like my corona
My ridge is dark purple and it looks very odd compared to the rest of the penis head. I would have killed for a beautiful penis head but nope. After years of phimosis, I finally get to see my gland and what do I get? An odd coloured corona. Hurrah! I have seen pictures of other people with this "condition" and most of them have or have had phimosis, so I think that there might be link.