Normally, they look like this http://www.pbase.com/britestar/image/102667118 with the main color being brown.

However, this individual "morphed" to display beautiful blue colors.
Unlike the Common Buckeyes in this article http://www.butterflyfunfacts.com/blue-buckeye-junonia-coenia.php , this butterfly was not selectively bred.

Found in Missouri, this seems to have been a natural occuring mutation. I discovered the article only after I had taken the photo and was doing some research to see if the butterfly could really be a mutation of a normal Common Buckeye.