The ${\mathrm{Cr}}^4$-doped yttrium aluminum garnet (${\mathrm{Cr}}^4\text{:}\mathrm{YAG}$) saturable absorber, a new generation of passively $Q$-switched solid-state laser material, faces a significant obstacle of low conversion rate of chromium from trivalent to tetravalent, degrading efficiency in a passively $Q$-switched laser. In this paper, highly transparent ${\mathrm{Cr}}^4\text{:}\mathrm{YAG}$ ceramics were fabricated and committed to compare the laser performance with ${\mathrm{Cr}}^4\text{:}\mathrm{YAG}$ crystals on a 1 μm passively $Q$-switched laser. Thanks to the grain boundary effect, the ${\mathrm{Cr}}^4$ conversion efficiency of 0.05 at.% ${\mathrm{Cr}}^4\text{:}\mathrm{YAG}$ transparent ceramics coated with high transparency (HT) films ($T=86.46\%$ at 1064 nm) was nine times higher than that of 0.1 at.% ${\mathrm{Cr}}^4\text{:}\mathrm{YAG}$ single crystals coated with HT films ($T=84.00\%$ at 1064 nm). Differing from the counterpart ${\mathrm{Cr}}^4\text{:}\mathrm{YAG}$ crystals, no absorption saturation tendency was observed for the 0.05 at.% Cr:YAG ceramics when the pump power exceeded $～1900\mathrm{mW}$. Furthermore, the repetition frequency reached 217 kHz for 0.05 at.% Cr:YAG ceramics, which was a three-fold factor increase from that of the corresponding single crystal. The advantages of transparent ceramics over single crystals were proved through laser performance for the first time, to the best of our knowledge. This study also provided compelling evidence for replacing single crystals with ceramics for u