GEMS

Below is a list of gems that would be good for casters. Most run about 50g on the AH except the meta which is about 150g.

Ember Skyfire Diamond
+14 Spell Damage 2% Intellect
Requires at least 3 Red gems
“Meta”

Runed Living Ruby
+9 Spell Damage
"Matches a Red Socket."

Unstable Topaz
Binds when picked up
+5 Spell Damage and +4 Intellect
"Matches a Red or Yellow Socket."

Brilliant Dawnstone
+8 Intellect
"Matches a Yellow Socket."

Dazzling Talasite
+4 Intellect and +2 Mana every 5 seconds
"Matches a Yellow or Blue Socket."

Glowing Nightseye
+5 Spell Damage and +6 Stamina
"Matches a Red or Blue Socket."

Solid Star of Elune
+12 Stamina
"Matches a Blue Socket."

Stormy Star of Elune
+10 Spell Penetration
"Matches a Blue Socket."

This is just reference for me:

Head:
Meta
Red

Shoulders:
Blue
Yellow

Chest:
Red
Yellow
Yellow

Wrist:
Red

Feet:
Blue
Yellow