The composition of the fluid phase in inclusions in synthetic HPHT diamonds grown in system Fe-Ni-Ti-C.

Diamonds grown by high pressure high temperature process (HPHT) are usually characterized by yellow color and high contents of nitrogen. Introduction of Ti decreases nitrogen content in diamond. Understanding the formation of nitrogen-poor diamond is very important not for the progress of HPHT process only, but because these diamond varieties represent the rare natural stones, although their crystallization conditions have not been clarified yet.

Carbon and Nitrogen Speciation in N-poor C-O-H-N Fluids at 6.3 GPa and 1100-1400 °C.

Deep carbon and nitrogen cycles played a critical role in the evolution of the Earth. Here we report on successful studying of speciation in C-O-H-N systems with low nitrogen contents at 6.3 GPa and 1100 to 1400 °C.