World biggest social network Facebook have not facilities for comment and status update in other color expect Black(default).But i have one idea for comment in blue color.
Step 1. Copy the given code and past it where you want to write in blue color.
@[1: ]@@[1:[0:1: Your Text Here]]
Step 2. Write the status of Comment insert the code Your Text Here.
Step 3.Look at the comment or status.