This process, called HPHT (high temperature high pressure) is usually applied to diamonds that have proven to be of a rare, specific crystal-structure which industry experts have named Type II. Diamonds that belong to this rare and unique category are most often above quarter pointers (above 0.25ct.), while showing few internal blemishes.
In soaking treatment,
This process is used to create white or near white diamonds using the HPHT treatment.
A type IIA diamond can be converted into Bright White colour while all other diamonds except type II can be converted to greenish, yellow or orange-yellow and pink colors. Although this process can create beautiful colors, it results in frosting of diamond surface that requires a re-polish and may also result in marginal weight loss and clarity degradation.
In short, these diamonds are of high quality and hard to find. In practical terms, the HPHT process generally improves the color of these Type II diamonds, sometimes slightly, at other times changing the color dramatically, turning a light brown stone into a top color stone, defined as a F, E or even D colour.
- It gives you an opportunity to buy a diamond that is of a significantly higher clarity, a better color grade and most probably larger than the non-processed natural diamond you had budgeted for.
- HPHT processed diamonds cannot reverse to their original state, meaning that the color – or "colorlessness" that is achieved by the process is permanent!