gems, bery, beryl, emerald, Zimbabwe, Sandawana, analytical, provenance

Emeralds from the Sandawana mines in Zimbabwe display relatively low and consistent δ¹⁸O values (δ¹⁸O₍V‑SMOW₎ = +6.6‰ to +8.0‰), among the lowest recorded worldwide, despite the global range for emeralds spanning from +6.2‰ to +24.7‰. These low values are attributed to host-rock buffering within a narrow reaction zone between albitised pegmatites and ultrabasic greenstones, specifically metamorphosed komatiites. The δ¹⁸O values of Sandawana emeralds overlap with those of emeralds from Brazil, Austria, Australia, and Madagascar, indicating that oxygen isotope composition alone is insufficient for geographic origin determination. However, emeralds with similar δ¹⁸O values can potentially be distinguished through a combination of physical characteristics, inclusions, and chemical composition.