A Gem Primer

A friend recently realized that when killing creatures in certain dungeons, she gets gear that can be socketed with gems to make the gear even more powerful. So, she said, what gems should I use? The answer, of course, is it depends.

The types of gem items

Gems as items, like other magical gear, can be green, blue, or purple, which represents uncommon, rare, and epic quality. The quality of the gem will determine its rarity, the amount of improvement it provides, and how much it costs. A raw gem is of no particular use until a jewelcrafter cuts it into a specific finished stone.

The color of gems

The color of gem slots may be red, yellow, blue, or meta. Meta slots hold special gems and are typically only found on head gear. Meta gems typically confer two distinct benefits. The color of a gem slot is important because socketing the correct color gem in a given slot(red-red) will activate a 'socket bonus': if every gem slot contains a matched gem you receive an additional stat increase, i.e. a weapon with a blue slot gives +7 haste if a blue gem is socketed.

Gems themselves may be red, yellow, blue, green, orange, purple, prismatic, or meta. Purple, orange, and prismatic gems are noteworthy for two reasons: First, they will match multiple sockets; second, they confer 2 attributes, one from each of the primary colors they represent. However, they provide less of each. Further, these hybrid gems count as either color when socketed.

Orange - will match a red or yellow slot
Purple - will match a red or blue slot
Green - will match a blue or yellow slot
Prismatic - will match any slot
Meta - matches a meta slot

Meta gems typically require a number of other gems of specific color to be 'activated'. For example, an Ember Skyflare Diamond requires three red gems to be active, that is, to confer +25 spell power and +2% Intellect. This could be any combination of three red, orange, or purple gems.

How gem naming works

Gem names are as follows:

[Perfect] (Description)(Stone Type)

Green quality stones are unique in that a jewelcrafter will occasionally cut a 'perfect' gem. For example, a runed bloodstone gives +14 spell power, while a perfect runed bloodstone gives +16 spell power. These represent an excellent value as they typically sell for a little more than the standard gem, but are almost as good as the blue quality gem selling for many times more gold. Blue and purple quality stones cannot be perfect, at least as far as I know.

The Description tells you what the stone does, that is, it tells you the attributes conveyed by the stone. All 'Reckless' stones, for example, will be orange stones that provide spell power and haste.

The Stone Type primarily identifies the specific stone, which will essentially indicate the quality of the stone and thus the magnitude of the benefit provided.

A bit more on gem quality

The quality of a gem determines its cost, but the benefit is subject to diminishing returns. For example(prices are AH average on my realm):

Runed bloodstone +14 spell power cost: 8-15 gold
perfect runed bloodstone +16 spell power cost: 12-20 gold
runed scarlet ruby +19 spell power cost: 60-100 gold
runed cardinal ruby +23 spell power cost: 200-250 gold

As you can see, the additional cost for 7 spell power(moving from bloodstone to cardinal ruby) is 200 gold. Yet many people will pay for it, and progression guilds will require blue, or now, epic, gems be socketed. My opinion, and advice, is to buy perfect gems when you can and use them on your average gear. Spend the gold on high level gems when you get a tier piece or other equipment that you anticipate using for some time. Not everyone agrees with this, but it is the most efficient plan unless you are pushing the limits of your class performance.

Where to get gems

The easiest place to get gems is the Auction House(AH). If you are there all the time, as I am, a quick scan shows you what is of interest to you, whether there are deals to be had, and what perfect gems are out there. If you see a deal, or something you want, and can afford it, pick it up. My assumption is that you know the general ranges of price and use Auctioneer and therefore have a good idea what is a deal and what isn't.

A better solution is available to anyone who is in a decent guild: either buy the raw gems (at lowest prices possible) from the AH, or get them from the guildbank stock, and have a guild jewelcrafter make them for you. This will lower your costs significantly and allow you to consider epic quality gems in your good gear, once you get it.

Another place to get gems is from Honor quartermasters and battleground quartermasters. You can buy epic raw gems for honor points in Orgrimmar, or wherever those Alliance dogs buy their honor gear, and then have the gems cut. This is an excellent value. The reason is that if you have been level 80 for more than a month and do even a moderate amount of PvP(i.e. Wintergrasp weeklies), you have probably purchased the best available honor gear and are honor capped. Epic gems are a way to spend honor and either improve your character or make some gold(they sell for ~200 each). Finally, cut meta gems and some other finished gems can be bought with shards from the Wintergrasp quartermaster, as can some enchants. Note that these are PvP-specific, but they are very reasonably priced.

What gems should I use?

This really depends on your class and your spec. As a destruction-specced warlock, I use mostly runed(+spell power) gems in red slots, reckless(+spell power + haste) in yellow slots, and purified(+spell power + spirit) in blue slots. The reason is that these all improve my spell damage or casting time. Specifically, they increase my primary and secondary attributes. You should determine which gems to use by reading up on your class and select gems of a color that matches your gear's sockets and provide the attributes most important to your class and spec.

Note that it is possible to socket all of the same gem in every socket. If the benefit of the primary stat is of key importance, and/or you don't have a meta gem socketed, and you don't care about the socket bonus, you could socket a specific gem in every socket(i.e red +spell power in all sockets regardless of color). However, if you are looking for multiple stats, then I think the hybrid color stones make more sense.

Hopefully this primer has given you a asic grounding in how to select, and what to look for, in gems. Good luck, and good adventuring.