The display of Messages, you can under OS X Mavericks in the change settings, and so other symbols activate. Then appears a colored icon to the right Status of the user. As the icons change, refer to the following Guide.

Mac OS X: icons for Messages, change

The popular chat program "Messages" can be colored icons for the Status of your contacts. This function you need the settings in the following ways:

Start Messages by entering the keyword "mail" in the Spotlight search at the top right corner. Here you select the first hit.
Now click in the Apple system tray on the "messages" and then select "settings".
Under the tab "General", you will now find the Central Option "icons in the status display to use". Put a check mark in the box.