I’ve made myself something of an expert on Jewelcrafting, ever since I wrote a levelling guide for jewelcrafting during the TBC beta (which is now somewhat error-prone thanks to Blizzard changing recipes and skill levels around; I’ll redo it someday).
There are a number of gem options that are suitable for healadin pallies, but you should make your choices carefully. Let’s look at a few of them:
The A Team:
[Teardrop Living Ruby]: red. +18 healing.
[Luminous Noble Topaz]: red, yellow. +9 healing, +4 int.
[Royal Nightseye]: red, blue. +9 healing, +2 mp5.
The three cuts above are all popular with paladin healers, and with good reason. Choosing between them is mostly a matter of personal taste, personal playstyle, and sometimes restrictions on gem color to activate a meta-gem or socket bonus.
[Dazzling Talasite]: yellow, blue. +4 int, +2 mp5.
[Gleaming Dawnstone]: yellow, +8 spell crit.
Both of these are decent second-string contenders, the talasite more so than the dawnstone. You wouldn’t want to focus on using either of these to the exclusion of the better gems, as your +heal would just fall too far; however, they can be useful to boost a problem stat (particularly the talasite) or to meet gem color limitations for socket bonuses or meta gems.
Do not, on the other hand, use [Lustrous Star of Elune]s. Compare them with [Royal Nightseye]s or [Dazzling Talasite]s; you lose 9 +healing or 4 +int, for what? One measly mp5. Don’t do it. (Also, do not even think of using a [Sparkling Star of Elune]. You will be fired from the paladin club. Seriously.)
Picking Your Gems
Unfortunately, for most holy paladins, there’s no One True Rule for picking gems to put in your healing gear. (The exception is for paladins in a decent amount of T6-level gear, who are advised to stack pure +healing gems, as they don’t generally have mana issues.) Instead, you should consider how fights generally tend to work out for you. Are you desperately throwing mid-rank Flash of Lights while desperately counting the seconds til your potion cooldown refreshes? You might want to add some +mp5 or +spell crit gems to extend your mana longevity. Are you having to use inefficient Holy Light spam just to keep a tank up? Throw in some pure +healing gems to increase your healing output, allowing you to use a more efficient spell rotation. None of the good pally healing gems is a bad choice; it’s just a matter of knowing your personal healing style and how it meshes with the rest of the raid team.
Now, if you look at this Elitist Jerks thread (which is some excellent healadin theorycrafting, if unfortunately aimed at players who have access to the best of the best gear), the poster sets up a system allowing you to numerically compare the value of different gems.
If you put a point value to the gems comparing blue vs epic, say 18 pts for a blue to equate it to healing, you get the following level calculations:
1 healing = 1 pt
1 mp5 = 4.5 pt
1 int = 2.25 pt
1 spell crit rating = 2.25 pt
Because mp5 can only be applied in whole values however, the actual worths of mp5 on epic gems is greatly diminished because of the other stats you are loosing.
This is a really interesting system that’s good for comparing gems at a glance, but one of the big problems with it is that it gives +Int more ing than it deserves (because Int is magnified 10% by the Divine Intellect talent, and also contributes spell crit (from basic game mechanics), and damage and healing (from the Holy Guidance talent)). Weight
Systems like this are tempting, because it gives you one easy answer: Gem A is categorically better than Gem B, because the formula says so, so there. If you pick your gems based on this system you’ll wind up with a huge mana pool because of the way it favours +Int, and that will contribute to your spell crit and +heal — but, in my opinion, not by enough to warrant the loss of mp5 or +heal directly. Instead, you really need to examine your playstyle and the effects of that playstyle, and decide on gems for yourself. (Which is not to say you shouldn’t socket gems with +int on them; I’ve used quite a few. Just don’t use them to the exclusion of everything else.)
Why Purple Isn’t Always Better (But Sometimes Is)
There’s a strong temptation to make use of the epic gems that you get in Heroic instances. However, most of them aren’t that great, and are definitely inferior to using more appropriate rare gems.
Let’s look at a couple:
[Blessed Tanzanite]: red, blue. +11 heal, +6 sta.
[Durable Fire Opal]: red, yellow. +11 heal, +4 resil.
[Soothing Amethyst]: red, blue. +11 heal, +6 sta. (This one’s actually from a Karazhan quest to kill Nightbane, not a Heroic drop.)
Don’t they look great? Look at that awesome +11 heal! And they’re epic!
…Yeah. And look at the other stats. +6 sta? +4 resilience? Useless to a PvE healer. (Unless you’re specifically gearing up a stamina set, of course, but as a general rule you shouldn’t be consciously sacrificing healing power for stamina unless your survival is more of a progression stopper than your tank’s is.) Leave the stamina and resilience for PvP healers, and stick with PvE healer stats.
On the other hand, there are some really really nice epic gems that are very suitable:
[Iridescent Fire Opal]: red, yellow. +11 heal, +4 spell crit. From Heroic Hellfire Ramparts.
[Rune Covered Chrysoprase]: yellow, blue. +5 spell crit, +2 mp5. From Heroic Shadow Labs.
These are both very tasty, because you don’t find spell crit on healer gems when you’re looking at the BoE gems from jewelcrafter cuts. (Don’t believe me? Check the chart!)
(There’s also [Luminous Fire Opal], [Royal Tanzanite] and [Dazzling Chrysoprase] from Shattered Halls, Slave Pens, and Old Hillsbrad heroics respectively. You should recognise all three as being epic ‘upgrades’ of the cuts recommended above in the ‘Choices’ section.)
There are two reasonable options in the meta gem selection (although many helms these days don’t actually have meta sockets).
[Bracing Earthstorm Diamond] – this gem is a lot easier to get now that the prerequisites have been relaxed (now it only requires more red gems than blue; it used to require more yellow gems than blue as well, which was very hard to juggle). However, it still requires some jiggery-pokery to get it working, and the reduced-threat bonus isn’t nearly as appealing for paladins as it is for other healing classes.
The most popular choice is [Insightful Earthstorm Diamond]. The Int bonus is nice, the proc goes off a lot, and the activation is easy to manage. It’s an all-around winner.
Socket Bonuses tend to act like a homing beacon. You see your shiny new shoulders with two yellow sockets, and you think “omg, must socket yellow gems!” and before you know it, you’ve put in two [Luminous Noble Topaz]es without actually checking to see if you need more int – or would mp5 suit you better?
There are some socket bonuses you just don’t need. For instance, I just picked up [Crystalforge Pauldrons] – two yellow sockets and a +4 stam socket bonus. I really don’t care about that 40 health, so I’m under no obligation to socket yellow-compatible gems in there. On the other hand, you better believe I stuck to the socket colors for my Mask of Introspection – the socket bonus is +9 healing; that’s half a rare gem right there!
In other words: yet again, there are no hard-and-fast rules. Look at the socket bonus and decide if it’s worth getting, then look at the gems you’d put in to achieve it, then decide if you’re sacrificing too much for the socket bonus to be worth it overall.