Top panel: reddening-corrected gravity-sensitive color difference ﹩{\left({c}_{1}\right)}_{0}﹩ vs. corrected ﹩{\left(b-y\right)}_{0}﹩ color index for BD+14°3061 (red) and two prototypical field yellow post-AGB stars: BD+39°4926 (blue) and HD 46703 (green). Overlaid is a grid of theoretical colors from Relyea & Kurucz (1978) for a metallicity of [Fe/H] = −2. Bottom panel: reddening-corrected metallicity-sensitive color difference ﹩{\left({m}_{1}\right)}_{0}﹩ vs. ﹩{\left(b-y\right)}_{0}﹩ for the three stars. Overlaid is a grid of theoretical colors from Relyea & Kurucz for a gravity of ﹩\mathrm{log}g=2﹩.