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How Are Lab-Grown Diamonds Made

Lab-grown diamonds, also known as synthetic diamonds or man-made diamonds, are created using advanced technology that replicate the natural conditions under which natural diamonds are formed inside the Earth’s mantle.

You might be wondering if you can create your own lab-grown diamonds at home. Unfortunately, in order to make lab-grown or synthetic diamonds, you will need highly advanced equipment and tools.

The two primary methods used to produce lab-grown diamonds are:

  • High Pressure High Temperature (HPHT) which mimics the natural conditions of how natural diamond are formed deep inside the earth.

  • Chemical Vapor Deposition (CVD) which involves breaking down carbon-rich gases into carbon atoms which are then deposited diamond seeds, layer by layer, gradually forming a diamond over several weeks.

Using High Pressure High Temperature (HPHT) To Create Lab-Grown Diamonds

Developed in the 1950s, the HPHT method was the first successful process for creating synthetic diamonds.

  • Process: This method mimics the natural conditions of diamond formation by subjecting carbon to high temperatures (about 1,500 degrees Celsius) and high pressures (over 1.5 million pounds per square inch).

  • Equipment: It involves using a press designed to create the necessary conditions. There are three main types of presses used: a belt press, a cubic press, and a split-sphere (BARS) press.

  • Steps: A small diamond seed is placed in carbon, usually in the form of graphite, and then exposed to these extreme conditions. The carbon melts and starts to form a diamond around the starter seed. It is then carefully cooled to form a pure diamond.

A BARS system Used In The HPHT Process

Using Chemical Vapor Deposition (CVD) To Create Lab-Grown Diamonds

This method was developed later than HPHT, becoming more prevalent in the 1980s and 1990s.

  • Process: This method involves breaking down molecules of a carbon-rich gas, like methane, into carbon and hydrogen atoms. The carbon atoms are then deposited on diamond seeds to form a diamond.

  • Equipment: A CVD reactor is used, in which the diamond seeds are placed on a substrate inside a chamber. Gases are then introduced into the chamber and energized to break down their molecular bonds, usually by microwave power or a hot filament.

  • Steps: As the gases break down, pure carbon adheres to the diamond seeds and gradually crystallizes. While the CVD process is conducted at lower pressures than HPHT, the temperatures required is still very high.

What Are The Differences Between HPHT Diamonds And CVD Diamonds?

  • HPHT Diamonds: Often produce diamonds with a yellowish or brownish tint due to nitrogen impurities. However, technological advancements have improved the color quality of HPHT diamonds.

  • CVD Diamonds: Generally produce higher quality diamonds with fewer impurities and better control over the diamond’s properties.

Both methods can produce diamonds of various sizes and qualities, suitable for different applications, from industrial uses to fine jewelry. The choice between HPHT and CVD often depends on the desired characteristics of the finished diamond and the specific requirements of the production.

In both HPHT and CVD, the resulting rough diamond is then cut, polished, and graded in the same way as mined diamonds. The technological advancements in these processes have made it possible to create diamonds that are chemically, physically, and optically identical to natural diamonds.

Lab-grown diamonds have become increasingly popular due to their ethical and environmental benefits, as well as their affordability compared to natural diamonds.


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