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Superdeep diamond contains remnants of mineral inclusions which suggest an origin 2 to 3 times deeper than normal mantle diamond, perhaps into the lower mantle. We report the first growth experiments for these deepest of all terrestrial samples. Multianvil press experiments were conducted over a range of pressures from 10-20 GPa and temperatures along a terrestrial mantle geotherm (T range~ 1800-2200oC). Two different carbon-saturated mixtures were used (a) metallic Fe-Ni and (b) simple Mgcarbonate. Carbon was supplied .