HPHT
High “Pressure” with High “Temperature” – Mostly processed in a Cubic
Press Models 650, 750 & 850.
HPHT Enhancements Use:
- Removal of Graining effect, as CVD Diamonds are grown layer-by-layer in low-pressure vacuum chambers without all-around containment, the layering creates a high to medium graining visual effect, the HPHT Treatment eliminates the graining visual effect.
-
Color Enhancements, one of the main gas components in growing CVD Diamonds is nitrogen
gas, the
higher the level of nitrogen gas the faster the growth process is, the most common high
nitrogen
growth recipe will yield near colorless or light brownish colors, the HPHT Treatment will enhance
the colors to Colorless.
The other common growth method is a recipe using even higher levels of nitrogen in the growth process yielding Dark Brown Color CVD that the HPHT Treatment will enhance the colors to various shades of Yellow, from Light to Dark Yellow as Brownish & Grayish Yellow. - Annealing irradiated Natural or all Lab Created Diamonds to Blue, Pink, Orange, Purple, Red & Green.
Advantages:
- High percentage success rate on treatments
- With the right treatment recipe, you can lower the nitrogen levels to extremely low levels.
Disadvantages:
- Medium to Very Strong Fluorescence is visible.
- Detectable.
- In some cases, repeat treatments can create clouds in the diamond that affect the Clarity Grade as affect the levels of Florescence.
- When HPHT Processing CVD Diamonds which have Polycrystalline Residue with in or on the surface of the Diamond from the CVD Growth Process, the Diamond could fracture or the Polycrystalline Residue could seem more visible or larger, this affects the Diamonds Clarity.
- Orange Color AS Grown HPHT Diamonds are HPHT Processed to Yellow, if the HPHT Diamond contain Metallic Residue, they will slightly fracture or get larger, or in repeat treatments the Diamond will become cloudy, in both cases this affects the Diamonds Clarity.