Given a resonance of known mass, width, and ${\mathit{J}}^{\mathit{P}\mathit{C}}$, we can determine its gluonic branching fraction ${\mathit{b}}_{\mathit{R}\ensuremath{\rightarrow}\mathit{g}\mathit{g}}$ from data on it s production in radiative vector quarkonium decay V\ensuremath{\rightarrow}\ensuremath{\gamma}R. For most resonances ${\mathit{b}}_{\mathit{R}\ensuremath{\rightarrow}\mathit{g}\mathit{g}}$ is found to be \ensuremath{\sim}10%, consistent with being qq\ifmmode\bar\else\textasciimacron\fi{} states, but we find that both pseudoscalars observed in the 1440 MeV region have ${\mathit{b}}_{\mathit{R}\ensuremath{\rightarrow}\mathit{g}\mathit{g}}$\ensuremath{\sim}1/2-1, and b(${\mathit{f}}_{0}^{++}$\ensuremath{\rightarrow}gg)\ensuremath{\sim}1/2. As data improve, ${\mathit{b}}_{\mathit{R}\ensuremath{\rightarrow}\mathit{g}\mathit{g}}$ should be a useful discriminator between qq\ifmmode\bar\else\textasciimacron\fi{} and gluonic states and may permit quantitative determination of the extent to which a particular resonance is a mixture of glueball and qq\ifmmode\bar\else\textasciimacron\fi{}. We also examine the regime of validity of PQCD for predicting the rate of V\ensuremath{\rightarrow}\ensuremath{\gamma}${\mathrm{\ensuremath{\eta}}}_{\mathit{g}\mathrm{\ifmmode \tilde{}\else \~{}\fi{}}}$, the ``extra'' pseudoscalar bound state which would exist if there were light gluinos. From the CUSB limit on peaks in \ensuremath{\Upsilon}\ensuremath{\rightarrow}\ensuremath{\gamma}X, the mass range 3 GeV\ensuremath{\lesssim}m(${\mathrm{\ensuremath{\eta}}}_{\mathit{g}\mathrm{\ifmmode \tilde{}\else \~{}\fi{}}}$)\ensuremath{\lesssim}7 GeV can be excluded. An experiment must be significantly more sensitive to exclude an ${\mathrm{\ensuremath{\eta}}}_{\mathit{g}\mathrm{\ifmmode \tilde{}\else \~{}\fi{}}}$ lighter than this.