The following is a basic guide to both gemming and enchanting your gear for the highest possible PvE dps. A PvP gemming guide will follow shortly. Keep in mind that all epic gems are available on Sunwell Island at the cost of 15 badges of justice, from bosses in Hyjal, Black Temple, and Sunwell Plataeu, and from your local auction house for a few hundred gold.
Meta Gem
+12 agility & 3% critical strike damage. Require 2 red gems, 2 blue gems, 2 yellow gems.
(Note – having an orange gem will count as having 1 yellow gem and 1 red gem. The same is true of purple and green gems.)
This is the best choice for any PvE situation. It provides the highest damage output. The meta that provides haste suffers from a hidden cooldown of 40 seconds and is inferior to this meta in every way.
Combat spec gem selection:
Red Sockets
rare: 4 agility / 4 hit – Glinting noble topaz
epic: 5 agility / 5 hit – Glinting Pyrestone
Yellow Sockets
rare: 8 hit - Rigid Dawnstone
epic: 10 hit – Rigid Lionseye
Blue Sockets
rare: 4 agility / 6 stamina – Shifting Nightseye
epic: 5 agility / 7 stamina – Shifting Shadowsong Amethyst
Mutilate gem selection:
Red Sockets
rare: 8 agility – Delicate Living Ruby
epic: 10 agility – Delicate Crimson Spinel
Yellow Sockets
rare: 4 agility / 4 hit – Glinting noble topaz
epic: 5 agility / 5 hit – Glinting Pyrestone
Blue Sockets