Soul Gems are stones that can store the souls of living creatures. Filled soul gems are used to create and recharge enchanted items while empty soul gems are used in a number of Atronach Forge Recipes. They can also be sold.
Soul Gems come in different sizes. The larger the stone, the larger the soul it can store, although larger gems can also hold smaller souls.
To fill a soul gem, cast the Soul Trap spell on a creature, then kill it before the spell wears off. If you have an empty Soul Gem in your inventory that can hold the creature's soul, the soul will be bound to the gem. If you have several Soul Gems, the creatures soul will be stored in the smallest gem that can hold it.
There are five levels of Soul Gems:
- Petty Soul Gem grants 150 charges
- Lesser Soul Gem grants 300 charges
- Common Soul Gem grants 800 charges
- Greater Soul Gem grants 1,200 charges
- Grand Soul Gem grants 1,600 charges
Note that most Soul Gems can only hold the souls of living creatures. Only Black Soul Gems can hold the souls of humans. Undead, Dwarven constructs, and some other creatures don't have souls that you can capture.
There are six types of Soul that can be captured.
There are two uniquely reusable Soul Gems the Azura's Star and The Black Star. These items can be acquired via alternative endings from the The Black Star (quest). This quest is given from Aranea Ienith at the Shrine of Azura South of Winterhold.
- Azura's Star can be acquired by returning the Broken Azura's Star back to Aranea Ienith, this ending also allows you to recruit Aranea Ienith as your companion. The Azura's Star can hold up to a Grand Soul Gem but is restricted to monster and other non-humanoids.
- The Black Star can be acquired instead by giving the Broken Azura's Star to Nelacar the banished mage in Winterhold at The Frozen Hearth inn. This item is a reusable Black Soul Gem that can capture humanoid type mobs and also can capture normal souls; Soul's captured grant enchantments up to a Grand Soul Gem level.