Earth functions as a coherent, self-regulating vector system. Its magnetic field, plasma environment, rotation, geology, water cycles, and biosphere operate as a unified phase-locked structure. This paper presents a geometric model of Gaia as a diamond-phase body: a planetary-scale coherence state formed through tetrahedral and octahedral vector alignment. Geological eras, biological evolution, and human consciousness reflect progressive stabilization of this planetary coherence. Gaia does not evolve by accumulation, but by alignment. planetary coherence, Gaia theory, vector coherence theory, diamond planet, planetary geometry, octahedral symmetry, tetrahedral Earth, magnetosphere dynamics, planetary plasma, Earth as organism, rotational coherence, geomagnetic alignment, biosphere conductivity, carbon cycle coherence, geological phase transitions, planetary nervous system, solar–Earth coupling, Schumann resonance, climate stability geometry, planetary resonance, coherent evolution, Earth systems coherence, crystal planet, living Earth, field-based planet, planetary phase locking, environmental coherence, Gaia consciousness, tectonic geometry, mantle dynamics, plasma boundary, planetary symmetry, biospheric regulation, magnetic field geometry, coherent eras, Earth maturation, vector-aligned planet, planetary stillness, planetary stability, rotational field theory, coherent Gaia, planetary diamond body, planetary awareness, Earth coherence model