Sapphire
Helm: +%dmg reduction
Weapon: +%IAS
Other: Cannot be Frozen/Jailed/Stun/Feared

Diamond
Helm: +%Resource pool (for example +10% AP/Mana/Fury etc)
Weapon: +%life steal +%resource steal
Other: +100 all resistance

What do you guys think? Will be something to introduce diversity over stat gems spam.