Abstract
The extremely complicated shapes of planetary nebulae revealed through the high resolution radio maps, direct imaging with the Hubble Space Telescope and observations with adaptive optics at large telescopes, are greatly different from their imagined simplicity long ago. To address the complexity in physical conditions and geometries of planetary nebulae, one must secure spectra of high spatial resolution and high dispersion. It also may require a long exposure even with a large telescopic aperture to reach faint features. We briefly review plasma diagnostics and a diagnostic possibility of iron ions based on our recent high dispersion spectroscopic work.