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How to make lab-grown diamonds

June 23, 2022

There are two main processes for manufacturing diamonds in the laboratory

1. High Pressure High Temperature (HPHT)
With this method of manufacturing synthetic diamonds, the laboratory simulates the high temperature and pressure conditions that occur when natural diamonds are formed underground. HPHT diamonds are produced at a pressure of 5-6 GPa (approximately equal to the pressure generated by a commercial jet aircraft parked at a person’s fingertips) and a temperature of 1300-1600°C.

Both lower quality natural and synthetic diamonds can be processed by the HPHT process to improve color and clarity. In addition to improving the color grade of colorless diamonds, the process can be used to change the color of the diamond to pink, blue or yellow. These diamonds are called “treated” diamonds.

lab-grown diamonds

2. Chemical Vapor Deposition (CVD)
With this relatively new technology, scientists are able to create synthetic diamonds at moderate temperatures (700°C to 1300°C) and low pressures. The carbon-containing gas is pumped into a vacuum chamber and deposited on the diamond crystalline seeds, which crystallize into synthetic diamonds. The final size of the diamond depends on the allowed growth time.

How to Identify Lab-Made Diamonds How to Identify Lab-Made Diamonds?

To the naked eye, a synthetic diamond (left) looks the same as a natural diamond (right).

To the naked eye, lab-created diamonds look exactly the same as natural diamonds. Usually, they can only be identified by using specialized instruments in gemological laboratories. These instruments can detect minute differences in trace elements and crystal growth to determine whether a diamond is synthetic or natural.