Epic gems and the missing spell power


It’s a bit of a convoluted story so i’ll try and start at the start and keep it short.

When looking at stat weighting for priests (notice an obsession here yet?) one thing that is argued about no end, but with no definitive or agreed answer, is the ratio between throughput and mana regen.  This is basically a magic ratio which joins heal equivalence points (HEP) and mana equivalence points (MEP) allowing comparison and conversion between the two.  Previously i’ve used a spell power to mana regen ratio of 0.6.  Others have argued for ratios more like 1.5 or have suggested the item budget ratio used by Blizzard be used.

This last suggestion eventually got me thinking about exactly what was the item budget used for determining how much intellect or spirit or spell power on an item.

Gems are a clean example of the expression of item budget because they exist with one or two stats making solving the equation for how much spirit equals how much intellect equals how much spell power an easier one to do.  So I started with the proposed epic gems for 3.2 (which turned out to be lucky) and tried to solve their item budgets.  I don’t have any idea what the total item budget for an epic gem is, so I arbitrarily choose 100.   That could be 100% or it could just be 100.  In the end it doesn’t matter as they are effectively the same thing.

Edit: Following zustrekes comment i’ve changed the base to 20 instead of 100 for epic and 15.5 for rares.

With a bit of spreadsheet magic I came up with these weights for the stats:

  • Spell power = 0.833333
  • Intellect = 1
  • Spirit = 1
  • MP5 = 2.5

If you apply them to all the epic gems I was interested in you get this.

Rarity Gem SP Int Spi MP5 Total weight
Epic Luminous Flawless Ametrine 12 10 0 0 20
Epic Brilliant King’s Amber 0 20 0 0 20
Epic Royal Dreadstone 12 0 0 4 20
Epic Purified Dreadstone 12 0 10 0 20
Epic Seer’s Eye of Zul 0 10 10 0 20
Epic Dazzeling Eye of Zul 0 10 0 4 20
Epic Sparkling Majestic Zircon 0 0 20 0 20
Epic Lustrous Majestic Zircon 0 0 0 8 20
Epic Runed Cardinal Ruby 23 0 0 0 19.1667

To prove or test this I applied the same weights to rare gems like so:

Rarity Gem SP Int Spi MP5 Total weight
Rare Runed Scarlet Ruby 19 0 0 0 15.8333
Rare Luminous Monarch Topaz 9 8 0 0 15.5
Rare Brilliant Autumn’s Glow 0 16 0 0 16
Rare Dazzeling Forrest Emerald 0 8 0 3 15.5
Rare Purified Twilight Opal 9 0 8 0 15.5
Rare Lustrous Sky Sapphire 0 0 0 7 17.5
Rare Royal Twilight Opal 9 0 0 3 15
Rare Seer’s Forest Emerald 0 7.75 8 0 15.75
Rare Sparkling Sky Sapphire 0 0 16 0 16

So what does this tell me?  Well firstly there are a few issues with the stat weights.  Or rather not with the stat weights, but the stats themselves.  For the rare gems their total weights should be 15.5, but many are not.  A bit of work using MS Excels Goal seek function led to an interesting discovery.  That is that when the designers are doing their thing they usually round up. So:

  • Runed Scarlet Ruby should have 18.2 spell power, but it is rounded to 19
  • Brilliant Autumn’s Glow should have 15.5 intellect, but it is rounded to 16
  • Lustrous Sky Sapphire should have 6.2 MP5, but it is rounded to 7 (this is the reason the epic Lustrous Majestic Zircon looks so useless) as this gem is a bit, relatively over-powered
  • Seer’s Forest Emerald should have 7.75 for each of its intellect and spirit, but this is rounded to 8
  • Sparkling Sky Sapphire, like the Brilliant Autumn’s Glow, should have 15.5 intellect, but it is rounded to 16
  • Royal Twilight Opal is the exception, which was rounded down.  It should have 3.2 MP5 rounded to 4 MP5, but instead rounded down to 3 MP5.  Or 9.6 spell power rounded to 10 instead of down to 9.  Either way it was rounded down.  This gem is also the best example of why an item budget of 15.5 for rare gems makes more sense than 16.  If it was 16 this gem should have another full point of spell power on it.

The epic gems are less complicated and working on them first probably saved me some confusion.  They are all spot on except the Runed Cardinal Ruby.  This gem is a strange one because it can afford to have exactly 24 spell power, which would hit it’s item budget right on the dot, but for some reason it only has 23.

So once 3.2 lands and you are all busily acquiring Runed Cardinal Rubys to put on your gear just remember your being ripped off 1 spell power each time 😉

Gobble gobble.


5 Responses to Epic gems and the missing spell power

  1. sparklefreeze says:

    Lol, you know what.. That list looks like my best-sellers list on the AH. While I doubt people actually go calculate the values as you did, it’s somehow instinctive that people just know, somehow those epic rubies aren’t as good as they look.

    My reasoning for why Royal Twillight Opal was rounded down is that it’s probably because of how it looks on the tooltip if it were a 10SP +3MP5. Normally, double digits of SP on a secondary colored stone suggests epic quality; and that is probably how most people who do not have these spreadsheets would interpret it. (This the whole reverse theory of why something costs $9.99 instead of $10.00 at the mart) Hence, I assume Blizz didn’t want to mislead people into that and kept it at 9.

  2. zusterke says:

    A good observation indeed. I first noticed this when I started basing my theorycrafts on gem-costs rather than their effective stat costs.

    But I’m surprised you used spreadsheet wonder to achieve the weights. The wowwiki stat cost article gives exactly the data needed:
    Stat – Cost – How much you get for 1 point
    Int – 1.0 – 1
    Spi – 1.0 – 1
    MP5 – 2.5 – 0.4
    SP. – 6/7 – 1.167

    A rare gem has a an item budget of 16. Thus:
    Runed Scarlet Ruby – 18,67 SP – rounded up to 19 or 101.7% of budget
    Luminous Monarch Topaz – 9.33 SP + 8 int – rounded to 9 SP – 98.2% of budget
    Dazzeling Forrest Emerald – 8 int + 3.2 mp5 – rounded to 3 mp5 – 96.875% of budget
    Lustrous Sky Sapphire – 6.4 mp5 – rounded to 7mp5 – 109% of budget

    Epic gems have (seemingly) an item budget of 20. This would place all regen stats on 100% of their value, but SP is indeed a bit skewed. Hybrids that give Spellpower should have gotten 11.667 SP. Since this rounded up to 12, those gems have an increase in stats by 1.42%. The 23 SP gem should have gotten 23.33 and thus sits at 98.57% of its budget.

    Of course, if you would mix this with your stat weights for gear, then you could measure the exact value of each gem. These rounding errors on the stats of gem also occur on gear and thus it is not unexpected for a gem or item with a less favorable stat would win merely because it was rounded up instead of down. For gear, we are speaking of small differences. I think with gems this becomes more apparent as the rounding up or down has a bigger impact on the total budget of the gem and because you stack several gems (thus several times this difference) in your gear.

  3. BobTurkey says:

    I’m pretty sure those WowWiki numbers aren’t right. The spell power number is defninently wrong as its should be 5/6 or 1.2 SP per point.

    What is the source for the rare gem = 16 and epic gem = 20 item budgets? They sound appropriate. I’ll update the psot with these bases.

  4. zusterke says:

    Hmpf, truth is I tend to follow the numbers from wowwiki almost blindly. If you fear they are inaccurate then there’s little I can say 🙂

    They lack a slotmodifier for gems tho (or I missed it). That’s odd… I thought I had ready the slotvalue of gems somewhere but I can’t find any reference of it anymore. I fear that leaves me with only my assumption as resource 😦

    I’ll see if I can test their theory on several items and check its (in)accuracy. If it proves a decent theory then perhaps it can be used to reverse engineer the slotvalue of gems.

  5. BobTurkey says:

    Do that and let me know what you think.

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