Education

The Basics of HPHT

HPHT, or high pressure high temperature, diamonds can be natural diamond that have been mined from the earth with a special chemistry that allows for color change. They can also be lab-created or man-made. By using an advanced HPHT technology, Suncrest Diamonds can heat treat any natural or man-made diamond (similar to rubies and sapphires) to enhance or change a diamond's color.

How does HPHT work?
HPHT is the process to enhance diamonds, performed only on the highest quality natural or man-made diamonds with no inclusions and high clarity grades. The Suncrest process replicates similar geological pressure and temperatures (approx. 5000°F) as the earth to expose the true nature of the stone––thus finishing the process the earth began.
Diamond processing requires the application of extreme heat and pressure. Typically, a diamond is processed at a temperature of around 1400°C (2550°F). At room pressure, these extreme temperatures would cause the diamond to revert to graphite. Maintaining extremely high pressure during the process allows the diamond to remain in its natural form (see figure). This typically requires pressures of around 60 kbar (nearly 1,000,000 psi)—the equivalent of a 240 km (160 mile) high column of granite.

To achieve these extremely high temperatures and pressures simultaneously, Suncrest Diamonds uses proprietary cubic press technology. The cubic press consists of six large pistons, each of which is capable of supplying several thousand tons of force. Each piston pushes on a small tungsten carbide anvil, which in turn compresses a cubic pressure cell that contains the natural stone. As soon as the cubic press reaches the desired pressure, electric current flows through a resistance heater embedded in the pressure cell to generate the required high temperatures. These conditions are maintained long enough to ensure complete chemical restructuring and color perfection.