[en] Rare earth ions in crystals exhibit narrow spectral features and hyperfine-split ground states with exceptionally long coherence times. These features make them ideal platforms for quantum information processing in the solid state. Recently, we reported on the first high-resolution spectroscopy of single ${\mathrm{P}\mathrm{r}}^{3+}$ ions in yttrium orthosilicate nanocrystals via the ${}^3{\mathrm{H}}_4-<!--\; ???\; -->{}^3{\mathrm{P}}_0$ transition at a wavelength of 488 nm. Here we show that individual praseodymium ions can also be detected on the more commonly studied ${}^3{\mathrm{H}}_4-<!--\; ???\; -->{}^1{\mathrm{D}}_2$ transition at 606 nm. In addition, we present the first measurements of the second-order autocorrelation function, fluorescence lifetime, and emission spectra of single ions in this system as well as their polarization dependencies on both transitions. Furthermore, we demonstrate that by a proper choice of the crystallite, one can obtain narrower spectral lines and, thus, resolve the hyperfine levels of the excited state. We expect our results to make single-ion spectroscopy accessible to a larger scientific community. (paper)