How Are Lab Grown Diamonds Made?

Lab grown diamonds have become a hot sustainability topic and one of the fastest-growing segments of the gemstone industry. However, when they were first conceived in the 1950s, they were used as tiny industrial drills, lenses, and heat sinks in electronics. It wasn’t until the 1980s that man-made diamonds became commercially available. And as lab gemstone technology advances and making them on a large scale has become more and more viable, their use in jewellery has exploded. Here, we’ll break down exactly how these technologies consolidate a million/billion-year-long, relatively rarely occurring natural phenomenon into a few weeks.

Lab grown diamonds are made using two main methods: High Pressure High Temperature (HPHT) and Chemical Vapour Deposition (CVD). The growth time of lab diamonds starts at 2–10 weeks and can extend to a number of months, depending on the process used and the number of carats of the final gemstone. Created gemstones are considered more ethical because they are not associated with any of the human rights abuses, environmental damage, and other ethical issues associated with diamond mining. Increasingly, lab-created diamonds are no longer considered as synthetic, but as real diamonds.

Lab diamonds cost less when compared to mined diamonds because they are not in limited supply. In other words, they aren’t as rare. Nonetheless, they are desired by diamond shoppers due to their cost-friendliness and the fact that they can be made with specific characteristics and properties, making them highly customisable and allowing for more creative possibilities.

The High Pressure High Temperature (HPHT) method of creating lab-created diamonds involves recreating the conditions that exist in the Earth’s mantle where natural diamonds form. The process typically starts with a small diamond seed, which is placed in a chamber along with a mixture of carbon and a metal catalyst. The chamber is then sealed and heated to very high temperatures, typically around 1300 to 1800 degrees Celsius, and high pressures, typically around 50,000 to 85,000 atmospheres.

During this process, the carbon atoms in the mixture are forced to bond together under the extreme conditions, forming a diamond crystal that grows around the seed. The process can take several weeks or months, depending on the size and quality of the diamond being grown.

HPHT diamonds are highly inclusion-free and pure, and typically less expensive to produce than CVD diamonds. White diamonds made using this method can sometimes have a yellowish tint to them.

In the Chemical Vapour Deposition (CVD) process, a small diamond seed is placed in a chamber that is then filled with a mixture of gases, typically methane and hydrogen. The chamber is then heated to very high temperatures, usually between 600 and 800 degrees Celsius.

Under these high temperatures and pressures, the methane molecules break down and the carbon atoms they contain begin to deposit on the diamond seed. As the carbon atoms accumulate, they form a diamond crystal that grows on the surface of the seed. 

Created diamonds formed using the CVD method are typically extremely transparent and colourless, which is a sought-after quality in white diamond stones.

The main difference between HPHT and CVD diamonds is the method of growth. HPHT diamonds are created by replicating the conditions found in the earth’s mantle, whereas CVD sees carbon atoms deposited on a substrate through a chemical process.

From an appearance point of view, the main difference between HPHT and CVD diamonds is their hue. HPHT diamonds can be yellowish or brownish in colour, while CVD diamonds are usually colourless or near-colourless. This is because the high temperatures and pressures used in the HPHT process can cause structural defects in the diamond lattice, which can affect its colour. Additionally, CVD diamonds can be grown in a wide range of colours, including yellow, blue, and pink.

However, these differences are relatively minute to the naked, untrained eye. In principle, both HPHT and CVD-created diamonds are of exceptionally high quality due to their controlled formation environments. The final result, in both cases, is a diamond with few to zero eye-visible inclusions.

Just like earth diamonds, lab-created diamonds undergo strict grading evaluations. However, there are a few key differences with the standards used to grade natural diamonds. For example, lab diamonds are often graded as “F” or “G” in colour, which is considered near-colourless. These are less expensive than “D” or “E” colour diamonds which are considered colourless. Additionally, lab diamonds are often graded as “SI” in clarity, which means they have small inclusions that are visible under 10x magnification, but not to the naked eye.

After this, the grading process for man-made diamonds and natural diamonds converge, as the lab ones are also graded based on the 4 C’s of diamond grading: carat weight, cut, colour, and clarity.

If you’re interested in accessing ethical white diamonds for your sustainable jewellery business, Inter-Pacific is your partner in doing just that. We provide and source various types of coloured gemstones, including diamonds, emeralds, alexandrite, blue sapphires, padparadscha, rubies, and opal. The quality and size of the lab gemstones we offer are on par with the best in the market, at a percentage of the price of mined gemstones.