Rapid quenching of aerodynamically levitated melts was used to synthesize a range of Gd3+xAl5-xO12 precursor glasses with nominal compositions 0 ≤ x ≤ 0.7. For all compositions, transparent glass beads were obtained most reliably by using an oxygen gas jet, which affords a faster cooling rate than levitation in argon . A representative cooling curve for the formation of Gd3.2Al4.8O12 glass in an oxygen gas jet is shown in Figure , with a photograph (inset) of a typical glass bead. The slower cooling rates afforded by quenching in an argon jet produced fully-crystallized opaque beads with perovskite (GdAlO3) as the majority phase (see Supporting Information S2). We did not observe any intermediate quenching conditions that lead consistently to direct crystallization of garnet on quenching (in contrast to the YAG system where such a mechanism is readily accessed ). The glass transition and crystallization temperatures of 850(2) and 925(2) °C respectively were extracted from DSC curves (see Figure , and Supporting Information S4-S8). With the exception of x = 0.7 (see section 3.2), the glass beads crystallized fully into the garnet structure after heating for three hours in a muffle furnace at 950°C, as shown by the PXRD patterns in Figure , and had typical ceramic-type microstructures with no apparent residual glass at the micron scale (see Supporting Information S12).