The Insightful Earthsiege Diamond provides 21 intellect and a "chance to restore mana on spellcast." The words are vague but certainly appealing. The chance effect is unique among other level 80 meta gems; but as I said before, I hate this meta. The vague description is a siren's song, luring in innocent and unsuspecting priests.
Let me explain the details. The chance effect on the Insightful Earthsiege meta has a supposed 15 second internal cool down, which at +600 mana on proc, gives it the potential to provide an additional 200mp5. Don't be fooled! I've tested this gem rather thoroughly and the actual return averages to about 60mp5. Most tests yielded 3 to 4 procs in 3 minute test times, but there were several instances when I casted for a full minute and never saw a proc.
If you need some perspective, 60mp5 is about the mp5 you would get from the old all-star trinket, the Je'tze Bell. For more perspective, this is a third of the mp5 you'll see on trinkets valued in more recent content, such as Solace of the Fallen. Please don't let me be misunderstood at this point though - I do think that overall, a meta gem that functions as half of a trinket is pretty useful.
But don't forget the first part of the meta gem: 21 intellect. If you're not a big fan of cross multiplication, I can tell you that each point of intellect is worth about 15 mana points. Multiply that by 21 and you get 315 mana. The additional intellect will also give you a tiny benefit to mana regeneration and critical strike rating, but I have to stress the benefits are extremely small and only being noted to show they weren't overlooked.
So what you get from the Insightful Earthsiege Diamond is: 315 mana and an average of 60mp5.
Now you know the details on the Insightful Earthsiege, so let's talk about the competition: the Ember Skyflare Diamond and the Beaming Earthsiege Diamond.
The Ember Skyflare Diamond gives 25 spell power and 2% intellect. The Beaming Earthsiege Diamond gives 21 crit strike rating and 2% mana. For both gems, the mana you gain will be determined by your individual gear, so I cannot give you a universal bonus number to compare to the Insightful Earthsiege. So in this case, I will use myself as an example. I am a disc priest with around 24,000 mana, which many would consider low for tier 9 gear. (More explanation on this next week.) Based on my numbers, both gems net me about 480 bonus mana. That means for all you priests with 30,000+ mana pools, you're looking at a much bigger benefit (+600 mana) from the Ember Skyflare or the Beaming Earthsiege. For all priests who are in the process of gearing up, and have smaller mana pools, the number will scale downward appropriately.
There are also some marginal differences to note with these two meta gems. +2% mana will technically net you more mana than +2% intellect, but intellect will subtly benefit your mana regeneration (in addition to the marginal amount of crit I mentioned earlier when we spoke about the Insightful Earthsiege). Inside a raid or party with replenishment, +2% mana will grant a bigger (though still subtle) effect from replenishment. For my 24,000 mana pool, the difference between the Ember Skyflare and the Beaming Earthsiege was .8 mana. For the Ember Skyflare, the bonus mana regeneration while casting was +3 mana (not casting was +6), and the bonus crit from intellect was around .1%. There is a lot more math that can be discussed but it's better left to the best of theorycrafters.
So, if you're choosing between the Ember Skyflare or the Beaming Earthsiege, it really comes down to personal preference. Do you prefer to have an additional 25 spell power on every spell you cast? Or do you prefer an additional 21 crit strike rating? (21 crit rating is about .5% by the way) It's up to you, as both stats are beneficial to priest healers of either spec. It should be said, however, that the Beaming Earthsiege Diamond is sometimes hard to find. The design for the gem is a random world drop that was added in patch 3.0.8. If you choose to go with the Beaming, you may want to stockpile a few if you're not a jewelcrafter, as you may have trouble finding one later.
Anyway, in summary, the two metas give the following:
Ember Skyflare Diamond: 25 SP and 2% intellect.
Beaming Earthsiege Diamond: .5% crit chance and 2% mana.
Now the question is, how do these three meta gems stand up to each other? The Ember Skyflare and Beaming Earthsiege certainly trump the Insightful Earthsiege on bonus mana given the current gear levels of the average raiding priest, but neither the Ember nor Beaming have a mana return component. The Ember Skyflare and Beaming Earthsiege do not rely on a low proc rate, where as the Insightful Earthsiege does.
So... here is the reason I hate the Insightful Earthsiege Diamond - the dealbreaker that makes the difference between an innocent, ordinary meta gem versus a nefarious, plotting, top hat wearing meta gem: the blue gem activation requirement. Look over all three gems again. The Ember Skyflare requires 3 red gems to activate - the Beaming Earthsiege requires 2 red gems and 1 yellow gem - the Insightful Earthsiege requires 1 red, 1 yellow, and 1 blue. The average healer is more than happy to socket red gems. Yellow gems might be hit or miss, but there is a fine selection of orange gems if you don't want to go pure intellect or haste. Blue gems are very limited in versatility, though, and some of them are down-right bizarre. Did you know there is a Crit + Spirit gem?
Of course, to the average holy priest, all this QQ about blue gems not being versatile isn't a big deal since holy priests benefit from spirit in combat. If a holy priest wishes to activate the Insightful Earthsiege Diamond, whether he gems heavily for spirit or not, he will find there are particular pieces of gear (such as the tier 9 and 10 helms) where utilizing the blue socket bonus with a SP+Spirit gem makes sense due to the Spiritual Guidance talent. The same situation does not exist for discipline unfortunately. Trying to socket blue spirit gems is like trying to socket lumps of coal, and a prismatic Nightmare Tear offers no better options than a Seer's Eye of Zul. A discipline priest's best choices would be with a Royal Dreadstone or a Dazzling Eye of Zul, but ultimately it still clashes with the fact that discipline priests are not having mana problems. Neither are holy priests for that matter.
And this is the crux of my argument: if mana is no issue then the entire appeal of the Insightful Earthsiege Diamond is lost on me. This is why I go with the Ember Skyflare or the Beaming Earthsiege. My personal choice is usually dependent on the auction house prices at the time, but I do enjoy the Beaming Earthsiege since I run with a lot of haste. Also it's rare and thus cooler. (In a world of meta gems, the Beaming Earthsiege Diamond wears sunglasses... at night.)
But despite my preferences, this is where I have to tell you that I can't choose your meta gem for you. Whether you're holy or discipline, mana might be an issue for you for any number of reasons. You might have longer encounters because your raid dps isn't up to par. You might still be working on your gear and the mana return from the Insightful meta could far outweigh the bonuses you get from Ember or Beaming. You might
be too lazy to not have the resources available to utilize mp5 consumables for encounters that require more strain on your mana pool. There are so many variables to consider and they will vary for every priest. The purpose of this write up is to encourage you to weigh your meta options if you haven't already, and I hope that you will. And honestly, for all my hating, the Insightful Earthsiege meta was very good last year around this time when we were still in Naxxramas. Our gear is better now though, so you may find you have a lot more flexibility available to you and can allocate more stats to help your raid instead of your mana pool. Think it over.
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