I have a couple of Icelandic hens with that coloring but I've also seen other non-Icelandic breeds with that coloring, too. With such a wide array of coloring, the Icelandics can be difficult to completely pin down unless you know that lineage of the bird. Good luck with her - she is a beauty!
*Beautiful Roos - always a hard choice in deciding what you want to keep. I know I have that problem with my Icelandics cockerals. We have a couple more that will have to go to freezer camp soon, but I need to make room in the freezer first.