Diatomic dications AY2+, where A = Ne, Ar, Kr or Xe and Y = C, N or O, have been detected and characterised via appearance energies, ionization energies of the corresponding monocations determined by charge-stripping, and values of translational energy release accompanying unimolecular dissociation of AY2+ on the microsecond timescale. The mechanism of formation of AY2+ is unclear, but possible involves three-body association of A2+ and Y. Approximate potential curves for some of these dications have been generated using the semi-empirical procedure due to Hurley, and applied in a general interpretation of some of the trends observed.