A Greater Jeweller's Orb can be obtained as a drop from slain monsters, chests, and various containers found throughout the game world in Path of Exile 2. They may also be acquired from specific sources like strongboxes or through vendor recipes and trading with other players.

The primary function of the Greater Jeweller's Orb is to increase the number of sockets on a skill gem. When used on a three-socket skill gem, it adds a fourth socket, expanding the gem's potential for support gem combinations and enhancing the player's ability to customize their skills.

It’s important to note that the Greater Jeweller's Orb only works on skill gems that already have three sockets and does not affect equipment or items. Additionally, the number of support gems that can be linked to a skill is limited by the number of sockets on the gem itself, making this orb a valuable tool for improving skill setups.

Due to its focused utility and limited availability, the Greater Jeweller's Orb holds value in both crafting and trading. Players often seek them out to optimize their key skills, especially when aiming for powerful endgame builds.

In summary, the Greater Jeweller's Orb is a valuable currency item in Path of Exile 2 that allows players to add an additional socket to three-socket skill gems. It plays an important role in skill customization and is a useful tool for enhancing character performance.