Comparing Methods - CVD vs HPHT Diamond

 The two primary methods of producing diamonds in a laboratory setting are chemical vapor deposition (CVD) and high pressure, high temperature (HPHT) synthesis. This article will examine the key differences between these approaches to growing diamonds artificially:

CVD Process

· Diamonds crystallized by depositing carbon gas onto a substrate in a vacuum chamber.

· Chambers contain hot filaments, microwaves, or plasma to break down gases.

· Common gases used are methane, hydrogen, and inert gas mixes.

· Temperatures sustained around 800-1200°C.

· A low-pressure environment enables uniform crystal formation.

· The growth rate is relatively slow at Under 1 carat per week typically.

HPHT Process

· Diamonds are formed by compressing carbon under extreme heat and pressure.

· Press machines generate pressures of ~60,000 atmospheres.

· Heating elements raise temperatures to 1500-2000°C.

· Graphite or diamond seed crystals are used as starting base.

· Metal solvents like Ni or Fe allow carbon transport to seeds.

· Higher growth rates - can produce over 3 carats per week per press.

 The CVD approach allows for good control over diamond shape, optical properties and crystal perfection. However, HPHT is better suited for producing large single crystal diamonds. In terms of costs, they are becoming comparable on a per carat basis as techniques advance.

 Combining these lab diamond production methods with traditional diamond cutting and polishing processes enables the creation of jewels indistinguishable from mined diamonds. Learn more about the science enabling wholesale lab grown diamonds by reviewing these detailed CVD and HPHT processes.