High-temperature and high-pressure (HTHP) experimental tool. (A) Illustration of a Bassett-type externally heated diamond anvil cell with some modifications. (B) Enlargement showing diamond anvils seated on WC or Si3N4 heating seats in the Bassett-type externally heated diamond anvil cell. A Y2O3-doped ZrO2 ring was used as thermal insulator. (C) Geometry showing the 160° scattering angle between the incident X-ray and fluorescence detector, as used by Bureau et al. (2007) and in the present study. The large melt globule should be in contact with both surfaces of diamonds.