Is the HPHT Diamond Process Secure and Irreversible?

HPHT processed diamonds cannot reverse to their original state, meaning that the color – or “colorlessness” that is achieved by the process is permanent.
When Type IIa diamonds are extracted from the ground, they often have a brownish tint from the constant exposure of minerals and soil that cause chemical reactions. The HPHT processing allows these stones to desensitize to and to materialize into their destined color. This is a permanent state and you should never be worried that time will change your diamond's appearance. 

Like all diamonds, HPHT diamonds are extremely durable. They can withstand extreme temperature and heat conditions, are resistant to general wear and tear, and require no special cleaning or care.