Eggfinity Stones (often called Stones for short) are items in Egg, Inc. introduced in Version 1.20 alongside Artifacts. They are one possible reward from launching Spaceships. Fragments of these stones can be obtained by consuming certain artifacts, e.g. consuming lunar totems gives lunar stone fragments to the player.
Certain Artifacts have sockets, and players can put Stones inside these sockets to enhance the effects of Artifacts. The first tier of each Stone is a Fragment. Stone Fragments cannot be placed inside sockets as they do not provide any bonuses. Stone Fragments must be used in the Hall of Artifacts in order to craft higher tier Stones.
It costs Golden Eggs to add a Stone to an Artifact, but it is free to remove the Stone from the Artifact. However, you will have to pay the cost of adding the Stone to the Artifact again if you want to put it back on the Artifact.
The effect of Clarity Stones add to each other, so 2 Clarity Stones allow the host artifact to have a 50% effect on the Enlightment Egg. There are theories about 3 Eggceptional Clarity stones to give a 300% effect to the host artifact on the Enlightment egg, but they have not been verified.