The solidification process of liquid garnets Ln3Al5O12(Ln = Dy, Y, Lu) was probed by differential thermal analysis. A critical temperatureTclgwas evidenced in the liquid. Cooling from temperatures underTclgleads to the crystallization of the single garnet phase. Cooling from temperatures aboveTclgleads to the solidification of a mixture of perovskite LnAlO3and aluminum oxide α‐Al2O3. For Ln = Y, the results are in agreement with stable and metastable phase diagrams previously proposed. The YAIO3melt was shown to display a critical temperatureTclpalso. Its metastable solidification from temperatures aboveTclpleads to the formation of the perovskite at around 1550