Radiant Talasite

Spell penetration is not the same as spell hit. Raid bosses have an innate 17% resist chance against spells but this can only be overcome by spell hit up to a maximum of 16% reduction. Spell penetration does not affect this at all. Spell penetration is 99% a PvP stat vs other players that are stacking resist. Very very few bosses in 25 man raids have more resist than the amounts reduced by Curse of Elements and Curse of Shadows thus spell penetration adds nothing to your dps. In general, spell penetration is a near worthless stat for PvE. I believe the only relevant bosses that are affected

honestly, if id looked at your sockets and seen spell penetration gems, i wouldn't care about the bt/hyjal loot, I'd call you a confused sad player. Spell hit/crit/dmg > spell penetration in any raiding situation. In a raid, and with your gear, you probably shouldn't have any spell penetration gems. Assuming you're hit capped and actually have 1300+ spell dmg, crit is probably the way to go unless you want to go for the spell dmg record ;D