HPHT (High Pressure, High Temperature) Treated, Mined Diamonds
When a *Type IIa (2A) mined diamond is lower in color, a process can be used to treat the diamond and improve or reduce the amount of color. This process is called High-Pressure High Temperature (HPHT). The diamond undergoes intense pressure (70,000 atmospheres) and high temperature (3,682°F), which essentially continues the process diamonds go through as they’re forming inside the earth, and brings it to a more mature, colorless state.
*There are several types of diamonds, including Type Ia (1A) and Type IIa (2A). Type IIa is the rarest type of diamond and only makes up about 2% of all mined diamonds. Because of its pure carbon chemical structure, it is the only type of diamond that can be used to grow new diamonds (see Lab Grown Diamonds) or treated to improve the diamond’s color.
Once a diamond has been treated to improve the color, the process cannot be reversed. The change is permanent and the new, better color is the official color grade of the diamond.
Because the process is irreversible and harmless to the diamond’s beauty and durability, it is the only diamond treatment the Gemological Institute of America (GIA) will provide a diamond report on.