CVD Diamond Growth: The Physics of Chemical Vapor Deposition

Unlike HPHT growth, chemical vapor deposition (CVD) grows diamond at lower pressures in a chamber containing hydrogen and a carbon-bearing gas such as methane. GIA's process overview describes how carbon deposits on flat diamond seed plates over a period of weeks.

The CVD Synthesis Process

The CVD process is carried out in several key stages:

• Substrate Placement: Small, ultra-flat diamond seed crystals (often produced via HPHT) are laid out on a substrate holder.
• Gas Introduction: Methane (CH4) and Hydrogen (H2) gases are introduced into the chamber, which is depressurized to a fraction of atmospheric pressure.
• Plasma Activation: Microwave energy breaks down the gas molecules and creates the reactive species needed for diamond growth.
• Carbon Deposition: Carbon from the activated gas deposits on the seed and builds diamond layer by layer. GIA describes chamber temperatures of about 900°C to 1200°C for this process.

Post-Growth Color Tints

Some CVD-grown diamonds develop brown coloration associated with defects and may undergo post-growth annealing to modify that color. GIA's 2024 laboratory update explains that post-growth processing is common among CVD submissions and that laboratories use spectroscopy and imaging to identify growth and treatment features. S.RONEN DIAMOND LTD trades exclusively in natural stones; see our color guides for natural fancy color formation.