Which Gems should I keep ?

Hi

I'm pretty new to PoE and I'm wondering which Gems I should keep or how to determine how much they are worth. I'm talking about 0% quality Gems only here.

ty

Keep 2 of every gem. You never know what gem you will need in the future when trying out some new build.
Unless the gem has 10+% quality or is drop only (http://pathofexile.gamepedia.com/Drop_Only_Gems) it will get traded for 1 alch max if at all. Drop only usually go in the 2-4 chaos range (though knockback, punishment, devouring totem are hardly used and therefore in the 1 alch class; multistrike may get you a bit more than 2-4 chaos as it is sought after)

Rule of thumb: Keep those that you can't get from quest rewards.
But keeping atleast one of each gem won't hurt if you can spare the space.

For reference:

http://pathofexile.gamepedia.com/Drop_Only_Gems



More tips: If a gem is very easy to get from quest rewards (i.e. killing Hillock), then it is unlikely you well be able to sell it for 1 alc as quest gems usually are sold for. Use http://pathofexile.gamepedia.com/Quest_Rewards and your own discretion to help you decide which gems to keep.

Also add faster cast and faster attacks to that list. You want a lot of those gems if you're levelling up new chars, and often want more than one per character.

Other good ones to keep (because they're useful with so many different skills/builds) include:

Increased AoE
Spell Totem
Ranged Attack Totem
Critical Weakness
Faster Projectiles
Lesser Multiple Projectiles
Movement skills you like

thx a lot :) I'm gonna keep 2 of every gem and the gems you listed.