Socketed items are easy to identify as their names appear in gray text when highlighted. You may insert a gem into a Socketed item by left-clicking on the gem to pick it up, and left-clicking over the Socketed item to fuse the gem and the item together.

Socketed Weapons and Armor allow you to customize your armor and weapons giving it added magical properties such as enhanced statistics, resistances to attacks and more.

Only Helms, Armor, Shields, and Weapons can be socketed. Not all weapon types can be socketed. Throwing Weapons cannot be socketed. The max number of Sockets a Socketed Item will have is 6. Weapons and Armor will have a random number of sockets depending on how many are allowed. Armor can only have 4 sockets. Weapons can have up to 6 sockets. Items with more sockets might be harder to find and may require higher Difficulty Levels.

Item Quality
Socketed Items can be normal quality and superior quality.

Magic, Rare, Crafted, Set and Unique Socketed Items
Magic Items can have up to 4 sockets. Rare items are limited to 2 sockets. Crafted, Set and Unique items are limited to 1 socket in most cases. There are a few Set and Unique Items that have more than one Socket as a default ability.

Socketed Item Quest
The first quest in Act V allows players to socket any item that allows sockets. This quest may not add the maximum number of sockets.

There is also a Horadric Cube formula that allows items to be Socketed.

Gems
Precious gems embody innate magical abilities. When set into a socketed item these gems can add powerful magic effects. [Learn more about Gems.]

Jewels
Jewels are similar to Gems, except that instead of having predetermined magical abilities like a Gem, each Jewel possesses random magic properties, allowing you to bestow a wide variety of magical abilities to your Socketed Item. [Learn more about Jewels.]

Runes
Runes are small stones inscribed with magical glyphs that can be inserted into Socketed Items. Runes are different from other Insertable Items: not only do individual Runes have set magical properties, certain combinations (or Rune Words), when inserted into the appropriate item, in the proper order, give that item even more wondrous abilities. [Learn more about Runes and Rune Words].