Icons of beta sites are different form the icons given in the http://stackauth.com/1.0/sites . As example:
Original icon of the English Language and Usage isWhy?
http://sstatic.net/english/img/favicon.ico
where http://stackauth.com/1.0/sites gives the icon
http://sstatic.net/skins/sketchy/img/apple-touch-icon.png
