Gemming your gear can be a brainbusting endeavour. What gems are good for us? Which gems should go in which sockets? When is a socket bonus worth pursuing? I have a number of yellow gems in my gear, but it was only after I sat down and did the math that I decided to make some serious changes.

You may be sitting on an untapped potential. No doubt your two blue gems and 17 red gems are beneficial to you, but there are a few more points to squeeze out here and there. Whether you want to get your hands dirty, or simply want to have a table of reference, lets get our hands dirty and look at some gems!

There are a total of five gems that you could, should, would ever consider for your gear. These are pure spellpower, spellpower + spirit, spellpower + crit, spellpower + haste and hit. I suppose you could consider a spellpower + hit gem, but as with the pure hit gem, this is generally not something you would want to pursue. We have a lot of hit from gear anyways, and you should only resort to gems with hit on if you are missing the last few points. Even then, one might consider not caring about gemming to get that last two hit rating before the cap, because two spells missing out of 10.000 casts does not seem like a big deal. So for this post, we will focus mainly on spell power, haste and crit.

First, we must establish how much each stat is worth. Again we zoom back to the numbers provided by Elitist Jerks, which weigh our stats as follows:

Spellpower: 1.4
Haste rating: 0.9 (1.5 if not soft-capped)
Crit rating: 1.1
Intellect: 0.6
Spirit: 0.5

Next, we calculate the worth of each gem:

Spellpower = 23 x 1,4 = 32,2
SP/Spi = 12 x 1,4 + 10 x 0,3 = 21,8
SP/crit = 12 x 1,4 + 10 x 1,1 = 27,8
SP/haste = 12 x 1,4 + 10 x 1,5 = 31,8
SP/haste = 12 x 1,4 + 10 x 0,9 = 25,8 (above 400+ haste)

The numbers are quite clear: Spellpower takes the lead, followed suit by SP/haste if you are below 400 haste rating, and with SP/crit as a close contender. I have personally been soft capped on haste since late Naxxramas, so this hasn’t been an issue for me, and the major focus is then on pure spell power and SP/crit gems. Obviously, you will want to use two blue gems (SP/spirit) to activate your meta, and you should try and put these gems in an item where you actually benefit from the socket bonus. If you have three blue slots in your gear, you take the blue slots that lead you to an increase in spell power, and not the one that gives you +10 intellect.

Funny thing about socket bonuses, they can change the layout of our table above. Red is often the obvious choice for us, and it should be used in every red socket, but there are times where this little gem gets outshined by the runner-up. Its crucial to identify when one gem is better than the other, and it is worth to take a look at your socket bonuses before you simply smack your gear full of Runed Cardinal Rubies.

Lets say you have a yellow socket with a +5 spell power bonus. This is generally the lowest spell power bonus you will find (I don’t remember seeing any +3 SP bonuses), and it might be interesting to see how you could gem this. You could use a pure, red gem and simply gain 32,2 points (remember, we are talking item weights here, not DPS or stat bonuses per say), but then you would forfeit the socket bonus. Consider, instead, a SP/crit gem, which is already worth 27,8 points, and then add the additional 5 spell power: (12 + 5)x 1,4 + 10 x 1,1 = 34,8. What we find is that the SP/crit gem is better, marginally, but still better, than the pure spell power gem. Then again, it is an 8% increase in points, so across several yellow slots, it might prove to be beneficial. You would only do this if the socket bonus has +5 spell power or more, and only if you can actually get the socket bonus. Those pesky yellow/blue sockets are probably not worth pursuing.

What if you have an item with two yellow sockets? Two red gems would give you (32,2 x 2) 64,4 points, but no socket bonus. Two SP/crit gems would give you ((12 x 1,4 + 10 x 1,1) x 2) 55,6 points. This is 8,8 points below the pure SP gems, but we haven’t added the socket bonus yet. 8,8 points worth of spell power equals (8 / 1,4) 6,3 spell power, so it will be worth pursuing if the socket bonus offers you +7 spell power or more. If the socket bonus is something like +haste, +int or +spirit, its generally not worth it.

The actual differences can sometimes be quite small. You can go for the socket bonuses with +5 SP on dual yellow if you wish, and there will hardly be a difference, but if you really want to min/max a lot, this is probably something you would want to consider.

A TL;DR version for gemming:

Have two blue sockets with SP/Spi
Single yellow sockets, where you can score a +5 SP bonus, use SP/Crit
Dual yellow sockets where you can score a +7 bonus or above, use SP/crit
Red sockets (or blue/yellow sockets with bad bonuses) use pure SP

Please note: Crit is nice, but don’t overdo it. Spell power is still the most powerful stat you can get, point for point, and you will reach the soft crit cap at some point (42% crit fully raidbuffed). Crit doesn’t stop being useful at that point, because it still benefits wrath, eclipse proccing, moonfire crits (with tier 9) and especially with the 4pt10 bonus, but if you find that you are reaching the crit cap, you may consider ditching a few of your SP/crit gems. I’m still doing research on this issue, though.