Quality grants small bonuses to an item depending on the type of item, up to a default maximum of 20%. Martial Weapons gain 1% more Physical damage per Quality. Armours gain 1% more Armour, Evasion, Energy Shield and Runic Ward per Quality. Rings and Amulets have a number of possible quality types that provide bonuses to specific modifiers on the item. Flasks gain 1% more Life and Mana recovery per Quality. Charms gain 1% increased duration per Quality. Skill Gems or equipment that grant Skills grant a specific bonus to their Skill based on their Quality.

Certain items can be found Corrupted or made Corrupted using a Vaal Orb, changing their properties unpredictably. Most methods of item crafting and modification cannot be used on Corrupted items. There is no penalty for using Corrupted items.