HTHP (High-Temperature High-Pressure)

Developed by General Electric in 1999, this treatment involves high temperature (2000 degrees C) and pressure (70,000 atmospheres) and can lighten or remove the brownish hues in some Type IIa diamonds.

The brownish colour in Type IIa diamonds is caused by structural defects formed during crystal growth that can be repaired by this treatment, thus creating a whiter clearer diamond.

It can also be used to alter the colour of some type I diamonds without the need for irradiation.


Treatment List