High-Pressure High-Temperature Method vs. Chemical Vapor Deposition

Laboratory-grown diamonds are grown using two methods: High-Pressure, High-Temperature (HPHT) and Chemical Vapor Deposition (CVD).

High-Pressure, High-Temperature (HPHT) Method

The High-Pressure, High-Temperature (HPHT) method artificially replicates the temperature and pressure found 200 kilometers deep underground where natural diamonds form. A diamond seed is placed in a large mechanical press where it is subjected to high pressure and high temperature. The machine can generate extremely high pressure and temperatures, approximately 1300 to 1500 degrees Celsius and 40,000 to 60,000 atmospheres of pressure. The carbon lattice rearranges itself according to the diamond seed, transforming into a diamond. Layers of diamond crystals grow over time until the desired carat weight is achieved.

Chemical Vapor Deposition (CVD) Method

The basic principle of the CVD method is to place a diamond seed in an ion gas reactor in a vacuum and then inject a carbon-rich gas at low temperature. High thermal decomposition of methane gas creates a plasma of carbon atoms, allowing the carbon atoms to form a thin film on the diamond, thus depositing the diamond. Recommended reading:

• A Comprehensive Look at Lab-Grown Diamonds
• Why Lab-Grown Diamonds Hold Their Value So Well
• Lab-Grown Diamonds vs. Natural Diamonds: Debunking the Myths