An HPHT diamond is a lab grown diamond. HPHT stands for the technology used to create it: High-Pressure High-Temperature.As the name suggests, these lab grown diamonds are formed by exposing carbon to extreme pressure and heat. This was one of the first technology used to create diamonds in a lab, patented by GE in the 1950s.This is the technology we used when MiaDonna was first founded in 2005. However, the technology showed limitations in growing larger colorless diamonds, so in around 2010 we moved to CVD technology to create our lab diamonds.