Three modified chinese cubic HPHT presses used for the production of synthetic diamond.

Two typical colored HPHT synthetic diamonds as they are available commercially since the late 1980’s. The sample on the left is a high temperature annealed yellow synthetic diamond and the sample on the right is an as-grown type IIb synthetic blue diamond. Image: Dr. Thomas Hainschwang.

A 25-carat HPHT synthetic blue diamond crystal, grown by Andrei Katrusha at NDT in 2015/16. Image: Dr. Thomas Hainschwang.