Darren

I'm almost done with the last few achievements/trophies for skyrim, and I know that the Skull of Corruption can be unobtainable if you allow the ritual to continue.

If I acquire the rest of the daedric artifacts first, will reloading an old save and collecting the skull give me the achievement, or do I need to have all artifacts at the same time? (minus the already used and destroyed ones like the infinitum book.)