I'm in the Mzulft Observatory and have met Paratus Decimus. This is the second game of TESV I have played - first time around, no problem finding the focusing crystal. This time - it wasn't there. I am stuck, and can' go back to an earlier game in this round without starting all over again in a new game. There has to be a database or some command line entry to make it think I completed this quest so I can move on with the game. Does anyone know how to do either one?

Console command: player.setstage

The quest in question (I assume): http://www.uesp.net/wiki/Skyrim:Revealing_the_Unseen.

I am sorry - I can get to the command line, but it doesn't like whatever I put in for the quest and the stage. I just want to end the Revealing the Unseen quest - i put in player.setstage <11> which i thought was right, but that, and every variation I could think of, didn't work

try it without the player part. Should do wonders.