From Seed to Stone
Lab-grown diamonds begin with a tiny diamond seed - a thin slice of existing diamond material that provides the crystal structure for new carbon atoms to build upon. From this seed, two distinct technologies grow full-sized diamonds.
HPHT - High Pressure High Temperature
The HPHT method recreates the extreme conditions found deep within the earth's mantle, where natural diamonds form over billions of years.
- Preparation: A diamond seed is placed inside a specialised press along with a carbon source (typically high-purity graphite) and a metallic catalyst
- Compression: The press generates pressures exceeding 1.5 million pounds per square inch (approximately 6 GPa) - equivalent to the weight of a commercial jet balanced on the tip of a finger
- Heating: Temperatures rise above 1,500 degrees Celsius, melting the metallic catalyst and dissolving the carbon
- Crystallisation: Dissolved carbon migrates to the cooler diamond seed and crystallises, building the diamond atom by atom
- Growth: Over a period of days to weeks, the seed grows into a rough diamond crystal
CVD - Chemical Vapour Deposition
The CVD method builds diamonds from a gas, depositing carbon atoms onto a seed layer by layer in a vacuum chamber.
- Chamber setup: A diamond seed is placed on a substrate inside a sealed vacuum chamber
- Gas introduction: The chamber is filled with a carbon-rich gas mixture (typically methane and hydrogen)
- Plasma activation: Microwaves or hot filaments ionise the gas into a plasma, breaking the molecular bonds of the methane
- Deposition: Individual carbon atoms rain down onto the diamond seed, bonding to its crystal structure
- Layer-by-layer growth: The diamond builds upward, layer by layer, at a rate of approximately 0.1 to 10 micrometres per hour
After Growth
Once the rough diamond has reached its target size, it is removed from the press or chamber and undergoes the same process as a mined rough diamond:
- Planning: Gemologists analyse the rough to determine the optimal cut that maximises beauty and carat weight
- Cutting and polishing: Skilled diamond cutters shape the rough into its final form using laser cutting and precision polishing
- Certification: The finished diamond is submitted to an independent gemological laboratory (IGI, GIA) for grading and certification
The Result
The finished lab-grown diamond is chemically, physically, and optically identical to a mined diamond. No gemological test can distinguish between the two using standard equipment. The only difference is origin - and a certificate that proudly declares it.