Looks more like Amber to me.
The pictures in the Field Guides of Warriors are not always correct. The picture of Blackstar on the cover of Codes of the Clans shows that he has blue eyes. In Cats of the Clans, his picture is shown above, he has amber. On the cover of the rumored, upcoming Field Guide, Battles of the Clans, he has amber eyes again. I am not sure what color it is, because I don't recall it being mentioned in any of the books. Keep your eyes open, and remember, the Erin Hunters don't write the Field Guides, so stuff in those books may be wrong.