- Normally you cannot capture a black soul unless you have a black soul gem (which are hard to find), or the Black Star. Either version of Azura's Star will function as a reusable grand soul gem, however only the Black Star will allow you to capture black souls (and, although it may.
- A captured soul will be put in the smallest available soul gem that will hold it. So if you capture a lesser soul, and you only have a grand soul gem available, it will be automatically put in the grand soul gem. If you have a empty grand and lesser soul gem, a lesser soul will always be put in the lesser soul gem.
In The Elder Scrolls V: Skyrim for the PC, PS3, and Xbox 360, there is some debate as to what is better, The Black Star or Azura’s Star.
Grand gems hold any non-humanoid mobs, regardless of level; Black soul gems hold any mob—humanoid or non-humanoid—regardless of level; So if you want to use your grand soul gems efficiently, you'll want to reserve them for mobs level 39 or higher. But determining the mob's level is the tricky part. You can use the console command getlevel.
Skyrim Filled Black Soul Gem
Both of these special soul gems can trap any size of creature, and is never broken or consumed when you fill an item with it, essentially giving you infinite grand soul gems, however The Black Star is only supposed to trap humanoid creatures, and Azura’s Star is only supposed to trap non-humanoids.
The major difference however is that The Black Star is currently bugged and will trap any soul for all creatures, including non-humanoids. This makes The Black Star immensely better than Azura’s Star, at least until it is patched (which may be a while since it’s not exactly game breaking).
Personally though, even without the bug, I would prefer The Black Star since there is an abundance of humanoids in the game, and any human trapped in The Black Star regardless of level is an automatic Grand Soul Gem.
Skyrim Se Soul Gems
Black Soul Gem Skyrim Locations
To get The Black Star or Azura’s Star, you need to start the quest called The Black Star. Speak to Araneas at the Shrine of Azura, which is in the mountains directly south of Winterhold. Once the quest is complete, you will have the choice to return the broken Azura’s Star to Araneas or to a man named Nelacar in Winterhold. Returning it to Araneas yields Azura’s Star, and returning it to Nelacar will yield The Black Star.