php screws up utf-8 charachters from mysql database using mysqli


I have some chinese characters (e.g. 中文(简体)) stored in a mysql database with content type utf8_bin.

I am pulling from the database with this code:

if($stmt = $mysqli->prepare("SELECT c_color FROM colors")){
       //$ccolor is filled with question marks

What am I doing wrong? I have

header('Content-type: text/html; charset=UTF-8') ;

and the page is displaying Chinese characters on it. Seems like a problem with php.