How are Laboratory grown diamonds made?

Lab-grown diamonds
[Image courtesy - ALTR]

The ability to grow diamonds by mankind is an amazing feat, leaving many to wonder about the process or processes behind it. An inorganic substance that takes millions of years to grow, under the weight, pressure, and extreme temperatures of the entire Earth couldn’t possibly be grown by man, could it? Well, even in 2018, it’s certainly hard to believe that diamonds can be grown by man.

The processes described below have little to no meaning, influence, or importance to the average jeweler or consumer. They are mainly differentiated in gemological terms circles and for laboratories as a means of identification and separation in order to distinguish different growth processes between lab-grown diamonds and how they compare to mined diamonds.

With that being said, today, there are mainly two types of growth processes. One method of growth is called HPHT (High Pressure, High Temperature). The other is called CVD (Chemical Vapor Deposition). Both processes take several weeks to months or more to grow, are very capital intensive, and take place throughout the world.

 

HPHT:

HPHT is an acronym for “high pressure, high temperature.” According to GIA, “HPHT diamond growth takes place in a small capsule within an apparatus capable of generating very high pressures. Within the capsule, diamond powder starting material dissolves in the molten metal flux, and then it crystallizes on the seed to form the synthetic diamond crystal. Crystallization occurs over a period of several weeks to a month or more to create one or a few crystal.

Lab-grown diamonds
[Image courtesy – GIA]
Lab-grown diamonds
[Image courtesy – GIA] “In HPHT synthesis, a press (left) applies extremely high pressures and temperatures to a central growth chamber that contains the necessary ingredient. This results in synthetic diamond crystals with combinations of cubic and octahedral faces (center and right).” GIA
 

CVD (LPHT):

CVD is a acronym for “chemical vapor deposition” and LPHT is an acronym for “low pressure, high temperature.” According to GIA, “CVD diamond growth takes place inside a vacuum chamber filled with a carbon-containing gas, such as methane. A source of energy—like a microwave beam—breaks down the gas molecules, and the carbon atoms are attracted downward to flat diamond seed plates. Crystallization occurs over a period of several weeks to create a number of crystals at the same time. The exact number depends on the size of the chamber and the number of seed plates. The tabular crystals often have a rough edge of black graphite. They often also display a brown color that can be removed by heat treatment prior to faceting for gem purposes.”

Lab-grown diamonds
[Image courtesy – GIA]
“In CVD synthesis, deposition of synthetic diamond occurs from a carbon-rich gas onto a flat diamond seed surface. The synthetic diamond grows in thin layers, and its final thickness depends on the amount of time allowed for growth (left). This results in flat, tabular crystals (center and right) with exteriors coated in black graphite crystals.” GIA
No matter how you slice it, lab-grown diamonds are chemically, physically, and optically identical to mined diamonds. They represent a high value proposition, require zero mining, have no sourcing, ethical, or human labor conflicts, and are a technological feat of humankind. I believe we should be proud to live in a day and age where even something as prized and special as a diamond can be reproduced to such a high degree of accuracy.

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