Sup guys. Ok so, i dont know why, but my grand soul gems seems not working. i got an ebony sword with soul trap enchanment, 18 empty grand gem, but killing the humans doesnt grant me souls. it says "there is no soul gem big enough". So, i really dont know why. But black soul gems works on humans. I also couldnt find anything about this on internet. i am playing on ps3.

Oh [censored], nvm, seems like humanoids can only be captured by black gems..

But seriosly, i can almost swear i was capturing damn humans with grands 1.5 year ago.. Sorry, my mistake^^

Grand soul gems don't work on humans. Only black soul gems can trap human souls.

If going Grand Soul hunting, search for Mammoths, Falmer Shadowmasters (the ones with the Falmer Helmet), and Falmer Warmongers.

Black Soul Gems are only able to hold Black Souls. NPCs have black souls. Lesser/Petty/Common/Greater/Grand Soul Gems only hold White souls. Monsters have White souls.

At level 30+ Draugr can be grand too.

Only Draugr Death Overlords and Dragon Priests. Oh, and the Full Power U-Force Archer.

All of the playable races are protected by the edicts of Arkay and can only be trapped using necromantic black soul gems.

Presumably first developed by the Sload, used by the Ideal Masters and since the Warp in the West they can be created through ritual on Tamriel during the Shade of the Revenant, when Mannimarco's place in his orbit of Arkay blocks Tamriel from Arkay's influence.