Two kinds of phenolic resin, novolak and resets, have been studied wit
h an addition of cobalt at pressures between 2 and 4 GPa and at temper
atures from 1300 to 1900 degrees C, all under thermodynamically graphi
te-stable conditions. Diamond was synthesized from these resins which
had been pre-fired at 500-1000 degrees C. From such resins, carbon pre
cursors carrying a great number of radicals, being nearly free of hydr
ogen and oxygen, and turbostratic in structure, can be constructed. Th
e pressure-temperature conditions suitable for the diamond synthesis w
ere dependent on the pre-firing temperatures. The cobalt served as a c
atalyst-solvent, similar to the case of conventional diamond synthesis
from graphite under diamond-stable conditions. Well-defined single cr
ystals cube-octahedral in shape, measuring 0.3-0.7 mm across and class
ified as type Ib were obtained.