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.