Dunno what the wood is but I think it's bloody lovely, and a bloody lovely pen made with it.
Not so sure it is pink Ivory though, all the pink Ivory I have seen and used has been a bit more pink than that and close grained.
This looks a though it is a bit burry, a larger piece might well have shown off the pip in it too.
There is actually a number of woods that can have pink in them for various reasons.
Looking through the colouring I would like to think it could be Yew.
Neil's word would be final for me, what is it Neil??