Gems call to me mightily. My inner OCD REALLY wants to match the socket to get the bonus. It’s like winning a little mini-game. BUT my inner mathematician knows that sometimes (most of the time) it’s better to say “Damn the Torpedoes” and just jam a red gem in everything. Sokay. Here’s the proof.
If you start with a pawn scale (NOTE: THIS SCALE IS FOR DISCUSSION ONLY! IT’S POSSIBLY VALID -RIGHT NOW- BUT WILL PROBABLY BE INVALID AS SOON AS 4.0.6 DROPS)(Also note: I’ve used my Affliction scale for this.. but if you swapped this out you could use any scale for any class/spec to figure out your optimal gemming methodology)
This is copied directly from Elitist Jerks for pre-raiding gear.
Warlock_Affliction_PreRaid Int=2.9937 SP=2.4187 Haste=1.2767 Crit=0.9617 Mastery=0.9037 Sta=0.0262
Int is worth the most. So the “best” gem available currently is the Brilliant Inferno Ruby At +40 int, that gem is worth [40 int * 2.9937 scale value = 119.748 Pseudo Points(PP)] and matches a red socket.
If we are looking to match a yellow socket then our best bet is the Reckless Ember Topaz(85.408 PP)
If we are looking to match a blue socket then our best bet is the Timeless Demonseye(60.66 PP)
My gemming methodology:
If you can’t reach hit cap through gear selection, and reforging then gem for hit. Rigid Ocean Sapphire or Lightning Dream Emerald or Veiled Demonseye.
If the socket bonus is +hit then match the socket if you need that additional hit.
Match sockets to activate your meta gem (with the new ones it’s dead easy).
… if you have a yellow socket.. and you gem a Reckless Ember Topaz instead of a Brilliant Inferno Ruby you are losing out on 34.34 PP. In order for the socket bonus to make this up the socket bonus needs to be at least 12 int (34.34 PP/2.9937 scale value) or 14 spellpower or 27 Haste or 36 Crit or 38 Mastery.
… if you have a blue socket.. and you getm a Timeless Demonseye instead of a Brilliant Inferno Ruby you are losing out on 59.088 PP. In order for the socket bonus to make this up the socket bonus needs to be at least 20 int or 25 spellpower or 47 haste or 62 crit or 66 mastery.
If an item has more then one gem then make sure the value gained in matching the sockets is more than would be gained by just jamming reds.