Java 7 should have its own icon on the Mac's system preferences.
If you run the verification app on the java site (http://www.java.com/en/download/installed.jsp), does it recognise that you have Java 7 installed? (note that this will only work with a 64bit browser, i.e. not Chrome).
I'm afraid that the move to Java 7 has caused a lot of sweat and tears—if you get into difficulties, it can sometimes be easier to reinstall FM server.