High-pressure,high-temperature processing of low-nitrogen boron-doped diamond

We have studied high-pressure, high-temperature processing (7.0 GPa, 2000–2100°C) of low-nitrogen boron-doped synthetic diamonds grown in the Fe-Ni-C system (5.5–6.0 GPa, 1350–1450°C) with boron and titanium additions. The results indicate that, during the growth of low-nitrogen boron-doped diamonds, there is a competition between different acceptors (boron and nickel). The system of point defects and their distribution over the crystal are not influenced by the processing; the uniformity of coloration in natural diamonds is governed by the prevalence of octahedron growth sectors.