the globus cruciger or orb and cross.
Sovereignty of Spirit over Matter
The globe = the world, the material cosmos.
The cross = the divine principle, Spirit.
Together: Spirit reigning over Nature.
The completed Stone
Some alchemists used the orb-and-cross emblem to indicate the coagulated, perfected Stone, because the Stone was said to reconcile the four elements (cross) within the sphere (earth).
Christic Kingship
In Christian-Hermetic iconography it indicates Christ ruling the cosmos.
Alchemy internalizes this: the inner birth of the King within the alchemist.