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Eocene gem zircons from Reddistone Creek, Glen Innes, Australia, have been assessed for isotopic and chemical homogeneity by Secondary Ion Mass Spectrometry (SIMS), Isotope Dilution Thermal Ionization Mass Spectrometry (ID TIMS), Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS), and Wavelength Dispersive X-ray analysis (WDS). Sensitive High-Resolution Ion Microprobe (SHRIMP) SIMS data show that the U-Pb and Th-Pb isotope systems are homogeneous at the ion microprobe spot mass of a few ng for two zircons, AusZ2 and AusZ5, and that AusZ2 has good homogeneity in U, Th, and Th/U ratio. Twelve ID U-Pb TIMS analyses of separate 200–400 μm chips, measured in two different laboratories, show that AusZ2 has remarkable isotopic homogeneity at the sub-permil level, is concordant, and has a ²⁰⁶Pb-²³⁸U age of 38.8963 ± 0.0044 Ma (2σ; n = 12, MSWD = 1.01 …