Emeralds stack oddly, adding much more damage than you would expect. When multiple emeralds are socketed, the duration adds, and the damage is squared: 2 = 4x damage over 2 seconds, 3 = 9x damage over 3 seconds, etc. Adding other types of poison damage from jewels in armor/helms/shields, poison charms, unique armor, etc can create considerable, long-lasting damage.
| Quality | Weapon | Helm or Armor | Shield | Clvl Req | |
|---|---|---|---|---|---|
| Chipped | 
|
Adds 5 (5.9) poison damage in 1 sec | +3 to Dexterity | +12% Poison Resistance | 1 |
| Flawed | 
|
Adds 11 (11.7) poison damage in 1 sec | +4 to Dexterity | +16% Poison Resistance | 5 |
| Normal | 
|
Adds 17 (17.6) poison damage in 1 sec | +6 to Dexterity | +22% Poison Resistance | 12 |
| Flawless | 
|
Adds 23 (23.4) poison damage in 1 sec | +8 to Dexterity | +28% Poison Resistance | 15 |
| Perfect | 
|
Adds 29 (29.3) poison damage in 1 sec | +10 to Dexterity | +40% Poison Resistance | 18 |