Expert

Expert is the name of the third level in the Diablo 3 version 2 and Reaper of Souls system of difficulty. It increases monster hit points and damage, as well as boosting gold and experience rewards.

Diablo 3 and Reaper of Souls PC Difficulty Levels

This is a quick reference listing; see the difficulty article for full details.

Normal: 100% Health, 100% Damage, 0% extra gold bonus, 0% extra XP bonus
Hard: 200% Health, 130% Damage, 75% extra gold bonus, 75% extra XP bonus
Expert: 320% Health, 189% Damage, 100% extra gold bonus, 100% extra XP bonus
- Doubled bounty currency rewards for Expert and all higher levels.
Master: 512% Health, 273% Damage, 200% extra gold bonus, 200% extra XP bonus
- Imperial gems may drop instead of Marquise on Master and all higher levels.
Torment I: 819% Health, 396% Damage, 300% extra gold bonus, 300% extra XP bonus
- Torment+ enables class Set Items at lvl 60+, and at lvl 70+ possible Key and Organ drops, plus increasing bonuses to legendary drop rates and extra bonuses to legendary drop rates in Nephalem Rifts.
Torment II: 1311% Health, 575% Damage, 400% extra gold bonus, 400% extra XP bonus
Torment III: 2097% Health, 833% Damage, 550% extra gold bonus, 550% extra XP bonus
Torment IV: 3355% Health, 1208% Damage, 800% extra gold bonus, 800% extra XP bonus
Torment V: 5369% Health, 1752% Damage, 1150% extra gold bonus, 1150% extra XP bonus
Torment VI: 8590% Health, 2540% Damage, 1600% extra gold bonus, 1600% extra XP bonus

Expert also runs an 21% chance of Death's Breaths dropping, and a 7.2% chance for Legendary Materials, as of v2.0.3.

Diablo 3 Console difficulty levels

These are the values for the Diablo 3 console. The upcoming PS4 version of Reaper of Souls will have different settings, presumably much closer to what's seen on the PC in Reaper of Souls.

Easy: +0% Gold Find, +0% Magic Find, +0% Experience
Normal: +20% Gold Find, +20% Magic Find, +40% Experience
Hard: +40% Gold Find, +40% Magic Find, +80% Experience
Master I: +60% Gold Find, +60% Magic Find, +120% Experience
Master II: +70% Gold Find, +70% Magic Find, +140% Experience
Master III: +80% Gold Find, +80% Magic Find, +160% Experience
Master IV: +90% Gold Find, +90% Magic Find, +180% Experience
Master V: +100% Gold Find, +100% Magic Find, +200% Experience