A colossal underground crystal mine megacity built into a massive luminescent gem cave spanning kilometers, towering diamond skyscraper spires with integrated resonance-harvesting panels glowing soft prismatic white, suspended elevator-district platforms with floating crystal gardens between massive selenite pillar formations, sleek magnetic lev-craft gliding through holographic light between radiant gem platforms, tiny mine-engineers dwarfed by mountain-sized cathedral caverns navigating between illuminated extraction levels, deep cave obsidian and electric rainbow spectrum palette with soft refracted light filtering through infinite crystal formations, epic upward shot from deepest mine floor traveling through massive shaft elevators emphasizes impossible underground gem engineering scale, photorealistic, cinematic depth of field