You can insert a gem into a Socketed Item, enchanting it with powerful magical effects. There are five different grades of gems:
The higher the grade of the gem is, the stronger effects it will provide. Once you insert a gem into an item you can’t remove it from the socket.
You can upgrade a gem either by touching a Gem Shrine or by using the Horadric Cube. If you place three gems of the same type into your Horadric Cube, you can create a gem of a higher grade.
There are some demonic monster’s skulls that contain eldritch symbols. These skulls work the same way as the gems
| Gem | Req Level | Weapons | Shields | Helms and Armor | |
 | Chipped | 1 | Steals 2% life and 1% Mana | Attacker Takes 4 Damage | Replenish +2 Life +2 and 8% Mana |
 | Flawed | 5 | Steals 2% life and 2% Mana | Attacker Takes 8 Damage | Replenish +3 Life and 8% Mana |
 | Skull | 12 | Steals 3% life and 2% Mana | Attacker Takes 12 Damage | Replenish +3 Life and 12% Mana |
 | Flawless | 15 | Steals 3% life and 3% Mana | Attacker Takes 16 Damage | Replenish +4 Life and 12% Mana |
| | Perfect | 18 | Steals 4% life and 3% Mana | Attacker Takes 20 Damage | Replenish +5 Life and 19% Mana |
| Gem | Req Level | Weapons | Shields | Helms and Armor | |
 | Chipped | 1 | Attack Rating +40 | +8 Defense | +3 Strength |
 | Flawed | 5 | Attack Rating +60 | +12 Defense | +4 Strength |
 | Amethyst | 12 | Attack Rating +80 | +18 Defense | +6 Strength |
 | Flawless | 15 | Attack Rating +100 | +24 Defense | +8 Strength |
 | Perfect | 18 | Attack Rating +150 | +30 Defense | +10 Strength |
| Gem | Req Level | Weapons | Shields | Helms and Armor | |
 | Chipped | 1 | 1-3 Cold Damage for 1.0 seconds | Resist Cold 12% | Max Mana +10 |
 | Flawed | 5 | 3-5 Cold Damage for 1.4 seconds | Resist Cold 16% | Max Mana +17 |
 | Sapphire | 12 | 4-7 Cold Damage for 2.0 seconds | Resist Cold 22% | Max Mana +24 |
 | Flawless | 15 | 6-10 Cold Damage for 2.4 seconds | Resist Cold 28% | Max Mana +31 |
 | Perfect | 18 | 10-14 Cold Damage for 3.0 seconds | Resist Cold 40% | Max Mana +38 |
| Gem | Req Level | Weapons | Shields | Helms and Armor | |
 | Chipped | 1 | Poison Damage +10 over 3 Seconds | Resist Poison 12% | +3 Dexterity |
 | Flawed | 5 | Poison Damage +20 over 4 Seconds | Resist Poison 16% | +4 Dexterity |
 | Emerald | 12 | Poison Damage +40 over 5 Seconds | Resist Poison 22% | +6 Dexterity |
| Flawless | 15 | Poison Damage +60 over 6 Seconds | Resist Poison 28% | +8 Dexterity |
 | Perfect | 18 | Poison Damage +100 over 7 Seconds | Resist Poison 40% | +10 Dexterity |
| Gem | Req Level | Weapons | Shields | Helms and Armor | |
 | Chipped | 1 | Fire Damage 3-4 | Resist Fire 12% | +10 Life |
 | Flawed | 5 | Fire Damage 5-8 | Resist Fire 16% | +17 Life |
 | Ruby | 12 | Fire Damage 8-12 | Resist Fire 22% | +24 Life |
 | Flawless | 15 | Fire Damage 10-16 | Resist Fire 28% | +31 Life |
 | Perfect | 18 | Fire Damage 15-20 | Resist Fire 40% | +38 Life |
| Gem | Req Level | Weapons | Shields | Helms and Armor | |
 | Chipped | 1 | Damage vs. Undead +28% | All Resistances +6% | Attack Rating +20 |
 | Flawed | 5 | Damage vs. Undead +34% | All Resistances +8% | Attack Rating +40 |
 | Diamond | 12 | Damage vs. Undead +44% | All Resistances +11% | Attack Rating +60 |
 | Flawless | 15 | Damage vs. Undead +54% | All Resistances +14% | Attack Rating +80 |
 | Perfect | 18 | Damage vs. Undead +68% | All Resistances +19% | Attack Rating +100 |
| Gem | Req Level | Weapons | Shields | Helms and Armor | |
 | Chipped | 1 | Lightning Damage 1-8 | Resist Lightning 12% | Chance to Find Magic Items +9% |
 | Flawed | 5 | Lightning Damage 1-14 | Resist Lightning 16% | Chance to Find Magic Items +13% |
 | Topaz | 12 | Lightning Damage 1-22 | Resist Lightning 22% | Chance to Find Magic Items +16% |
 | Flawless | 15 | Lightning Damage 1-30 | Resist Lightning 28% | Chance to Find Magic Items +20% |
 | Perfect | 18 | Lightning Damage 1-40 | Resist Lightning 40% | Chance to Find Magic Items +24% |
