Pretty Soul Gems:
These consists of anything nature. They get the name pretty because in Skyrim the nature and life is "pretty"

Creatures that fill them- Elk, Wolves, Goat, Mud Crab, Slaughter fish, Rabbit, Deer, Skeevers, and Ice Wraiths.


Lesser Soul Gems:
These gems contain souls from creatures that attack on site, and will kill for no reason.

Creatures that fill them- Falmer, Falmer Skulkers, Atronach's, Spider's, Sabre-tooth Cats, and Chaurus Reaper.


Black Soul Gems:
These are filled dark souls, they are just evil.

Creatures that fill them- Necromancers, Dremora, Bandits, and Ghosts.



Common Soul Gems:
Just the common creatures of Skyrim fill these.

Creatures that fill them- Skeleton's, Troll's, Bear's, Draugr,( except Death Lords) Spriggan's, Hagraven, and Falmer Gloomlurkers.



Greater Soul Gems:
Still common around Skyrim just the larger of creatures.

Creatures that fill them- Giants, and Draugr Deathlords.



Grand Soul Gems:
Biggest and the best Soul Gem to have. Best for enchantments.

Creatures that fill them- Mammoth's, Falmer Shadowmaster's, and Dragon Priest's.