What could cause this purple color on my chickens comb edges?

If the back of the comb is dark, it might be stress or hormones. If the darkness moves up the comb it is a sign of a serious heart or lung problem. I had a hen die recently, and most of here comb was dark purple. what breed is it?

 

Our rooster's comb will turn purple on the edges like that when he is stressed (like when he is separated from his hens for a while ... for good reason). When he is put back with them it immediately turns back to bright red.

Oh, and