1939 Braunbeck’s extension showed that magnetic levitation is possible with diamagnetic materials
Groups with extended pi-delocalization have larger diamagnetic corrections compared to related saturated ligands.
Due to the changes in magnetic properties that occur from a spin transition - the complex being more diamagnetic in a LS state and more paramagnetic in a HS state - magnetic susceptibility measurements as a function of temperature are most commonly used in addition to optical spectroscopy and X-ray crystallography.