The Belarus producer ADAMAS has realized the synthesis of large diamond sin
gle crystals of up to 4 carat, having an extraordinary hardness in some par
ts of the crystals. This process was carried out at high pressure acid high
temperature, using the Russian BARS-technology. The special properties of
this process and the design of the reaction cell are published here for the
first time. Furthermore, preliminary results on the mechanical properties
and the structure and distribution of defects in diamond single crystals, t
hat were synthesized by this process, are given.