Before you decide to cut/buy some pretty gems for your tree, you need to figure out which stats are most important. Or read this post. Whatever :P So lets check out whats up there!
Spellpower – This is your bread and butter. This stat makes the world go round, etc etc. Spellpower gives you bonus healing on all your casted spells and hot's, etc, so the higher this is, the more powerful our heals are going to be. 1st priority.
Spirit – This is a way us trees will regen our mana. Roughly calculated 6 spirit = 1 MP5. You will find items and gems will give you more regen via MP5 then the Spirit alternative, However we have talents to increase our spirit by up to 15%, and raid buffs such as kings will also increase this amount, making it more rewarding the more you stack it. In raid gear this should be your 2nd priority.
Haste – Feel free to disagree with me here, as I know a lot of extremely strong druids that place this stat under Intellect. EJ gossip shows that with our 3/3 celestial focus and 5/5 gift of the Earthmother, our haste cap has crept up to a whopping 541. I place this stat as 3rd as It decreases the cast time of all our casted spells, and helps us toward the 1 second GCD we strive so hard to obtain.
Intellect – Ok so if you decided haste is more important to you then this is going to be your 3rd. Intellect will increase your mana pool giving you more mana to burn through during boss fights.
Critical Rating – Crit allows our casted spells and Lifebloom blooms to Crit! This includes your Nourish, Healing Touch, Lifebloom Bloom and the casted part of Regrowth. Our Tier gear always comes with it so you will get this naturally, I wouldn’t bother gearing towards it though cause chances are you would lose haste to do so.
So now that we have our list, what gems should go where? Here is my personal top 3 for each color.