There is currently no way to remove a gem once it has been placed into a socket. You can place another gem in the same socket, but doing so will destroy the existing gem (much like overwriting enchants).
Placing gems in sockets
Gems can be added to sockets in the "Item Socketing" window, which can be opened by holding shift and right clicking on a socketed item. The gems are then dragged into the slots, and the "Socket Gems" button is pressed to apply the gems.
Sockets are separated into three types:
Gems may be placed by anyone into a socketed item via a drag-and-drop interface, invoked by shift-right-clicking the weapon or piece of armor you want socketed.
Prismatic, or uncolored, sockets are (as of patch 7.0.3) the default socket found in any item with gem sockets. They can also be added to an item by blacksmithing skills (or blacksmithed items such as the ). Any gem (except meta gems) may be placed in them.
Items that has a Sha-Touched socket can have one prismatic socket added to them by using .
Cogwheel sockets are engineering-only sockets first introduced in World of Warcraft: Cataclysm. Any class is capable of adding cogwheels to these sockets, so long as they have the engineering skill to do so. Currently the only known items that have cogwheels are the epic helms crafted by engineers with 525 skill points.
- Main article: Meta gem
Meta sockets are only found on high-level head gear from The Burning Crusade to Mists of Pandaria (currently only in particular varieties of head items). Meta sockets only accept meta gems, and meta gems may only be placed in meta sockets.
Prior to patch 7.0.3, a meta gem introduced before Mists of Pandaria would be inactive unless certain requirements were not met, such as equipped items being socketed with a certain number and color of other gems.
This section concerns content exclusive to Mists of Pandaria.
- Main article: Sha-Touched
Prior to patch 7.0.3, the majority of sockets found on equipment were Red, Yellow, and Blue sockets. While any gem could be put in any of these socket types, the item socket bonus would only be activated if all of the sockets were filled with the matching gem color.
With the exception of meta gems, all gems matched one or more of these colors.
- Primary-color gems — red, yellow, and blue — would only match into the specific sockets for their color.
- Secondary-color gems — green, orange, and purple — would match into either of the two slots that correspond to their color. (For example, an orange gem would match a red or yellow slot for the bonus.)
- Prismatic gems would match any of the three socket colors.
Sockets were introduced in The Burning Crusade and modelled after a similar concept using gems in Diablo II, though the method of replacing them is different. The rune word system in the Diablo II expansion Lord of Destruction, which added additional bonuses if a particular set of runes was inserted in a particular order, has not been replicated in WoW — special combinations of gems do not confer any bonuses except the item's pre-defined socket bonus, unless using a meta gem.
As of patch 3.0.2, Blacksmiths with skill level 400+ are able to permanently place an additional socket on their bracer and glove, making the socketed item soulbound. Blacksmiths were originally given the ability to socket one-handed weapons, but this appears to not have been implemented in a patch release (although it is referenced in the game files).
A blacksmith with skill level 425+ can make an , which can be used by anyone (even sold via the Auction House) to add a prismatic socket to a belt, making the belt soulbound.