How Lab-Grown Diamonds Are Made

Natural diamonds form beneath the Earth's surface over billions of years, under immense heat and pressure. Lab-grown diamonds are created differently, using advanced technology to recreate the environment in which diamonds naturally grow.

The result is a genuine diamond with the same chemical composition, crystal structure and physical and optical properties as a natural diamond. The difference is how and where it is formed — beneath the Earth over billions of years, or in a carefully controlled laboratory environment over a matter of weeks.

There are two established methods used to grow lab-grown diamonds: High Pressure High Temperature (HPHT) and Chemical Vapour Deposition (CVD). Each uses a different process to create the conditions needed for diamond growth.

The science behind lab-grown diamonds

Natural diamonds form when carbon is subjected to immense heat and pressure deep within the Earth's mantle. Over time, carbon atoms arrange themselves into the distinctive crystal structure that gives diamond its exceptional hardness and brilliance.

Lab-grown diamonds begin with a small diamond seed. Rather than waiting for the natural process to take place over billions of years, controlled conditions allow carbon to crystallise onto the seed and form a diamond crystal.

High Pressure High Temperature (HPHT)
The High Pressure High Temperature (HPHT) method was the first commercially viable method for producing lab-grown diamonds and mimics some of the conditions under which natural diamonds develop.

A small diamond seed is placed inside a growth chamber alongside a carbon source and a metallic flux. The chamber is subjected to extremely high pressure and temperatures of around 1,300–1,600°C. Under these conditions, the carbon dissolves into the molten flux before moving towards the diamond seed, where it crystallises and gradually builds the diamond crystal.

Chemical Vapour Deposition (CVD)
The Chemical Vapour Deposition (CVD) method takes a different approach, growing diamond from a hydrocarbon gas mixture inside a vacuum chamber.

A small diamond seed is placed inside the chamber alongside carbon-rich gases such as methane and hydrogen. The chamber is heated to high temperatures, typically around 800–1,000°C, and microwaves are used to create a plasma that breaks down the gas molecules and releases carbon. The carbon then deposits onto the diamond seed, gradually building the diamond layer by layer.

Although HPHT and CVD use different processes, both produce genuine diamonds. The difference lies in how and where they are formed — with the diamond itself having the same chemical composition, crystal structure and physical and optical properties as a natural diamond.