Abstract: The onset of melting of beryl + H2O was determined experimentally in the P-T range 10–25 kbar, 900 to 1200°C, by synthesis runs on the composition Al2Be3Si6O18. Beryl begins to melt incongruently to chrysoberyl, phenakite, and melt at temperatures slightly above 1000°C. At higher temperatures a divariant stability field exists where beryl, chrysoberyl, phenakite, and melt coexist due to the solubility of H2O in beryl and in the melt. The final disappearance of beryl was bracketed between 1050 and 1100°C at 10 kbar and at 1100°C between 10 and 20 kbar. The phases (analysed for Al and Si by electron microprobe) do not show major deviation from stoichiometric composition.