Lab Grown Diamonds Fundamentals Mini Course
A Brief History of Lab-Grown Diamonds
What are Lab-Grown Diamonds?
As the name indicates, lab-grown diamonds (also known as synthetic diamonds) are created or "synthesized" in laboratories. To understand this process, you must first understand how natural diamonds form.
Natural diamonds form up to 150 miles below the Earth's crust, where carbon is compressed under extremely high temperatures and pressures. Scientists produce synthetic diamonds under the same conditions but in laboratories, using a variety of methods to compress carbon at high temperatures and pressures to make it crystalize.
The First Lab-Grown Diamonds
Scientists discovered diamonds consist of pure carbon in 1797. This started the race to create the first synthetic diamond. Throughout the 19th century, many attempted to recreate in a lab setting the conditions necessary for diamond formation. Although there were many claims of success, scientists couldn't replicate these experiments.
The first proven synthetic diamonds were made by GE in 1954, under a project codenamed "Project Superpressure." This project began in the 1940s, but World War II postponed the work. For years, scientists experimented with various methods, temperatures, and pressures to produce diamonds from carbon. Using a high-pressure belt press, they subjected small seed crystals to temperatures of 1,600º C (2,912º F) and pressure of 100,000 atm. In this device, they dissolved graphite — another mineral made of pure carbon — in metals, including iron, nickel, and cobalt, to accelerate the transformation of graphite to diamond.
When the resulting material broke the scientists' cutting tools, they believed they had succeeded. With a Mohs hardness of 10, diamonds can famously scratch and destroy metal tools. They subsequently confirmed that they had, indeed, made diamonds. A team of scientists, including both Herbert Strong and Howard Tracy Hall, received credit for this discovery.
The First Gem-Quality Lab-Made Diamonds
The diamonds GE produced via this process were far too small for gem use. Instead, they were used for industrial purposes. Nevertheless, this discovery paved the way for GE to create gem-quality crystals in 1971. Their process used a tube to add heat and pressure to a graphite seed in the center until it grew into diamond.
Although an incredible discovery, using such high-temperatures and pressures to produce these stones was too expensive to compete economically with natural diamonds. Furthermore, these first gem-quality synthetic diamonds were often yellow and also contained many inclusions. Such stones wouldn't receive high grades according to the color and clarity standards for white or colorless diamonds.
Research revealed an excess of nitrogen in the gems caused the yellow color. Some further adjustments lead to the production of colorless diamonds. Within a few decades, research by scientists in the United States, Russia, and China made it possible to create diamonds in laboratories that could exceed natural diamonds in carat (size), color, and clarity. Slowly, these gems made their way into the diamond market.
The method initially developed by GE is a high pressure/high temperature process (HPHT). This method mimics diamond-forming conditions underground. However, reproducing such conditions is expensive and complex. (In 1999, GE developed an HPHT treatment to improve the color of white diamonds).
Today, most lab-grown diamonds are made through a process called chemical vapor deposition (CVD). In this method, carbon gas heats a diamond seed in a chamber, causing the carbon to stick to the seed and grow into a larger diamond. CVD gives scientists more control over the properties of lab-grown diamonds and makes possible the production of large, gem-quality diamonds. CVD can also take place at lower pressure and temperature, which makes the process much less costly.
The first patent for CVD was issued in the 1950s. However, scientists didn't refine the process so it could produce gem-quality diamonds until the 1980s. It took even longer to make this process commercially viable, since only one seed could undergo CVD at a time. This was quite costly. Now, dozens of seed diamonds can undergo CVD at once. (The exact number is unknown and regarded as a trade secret).
Changing the Diamond Industry
Although lab-grown diamonds represent just a small percentage of today's market, the demand for these stones increases every year. Synthetic diamonds cost 30-40% less than natural diamonds, and growing consumer interest in ethical diamond sourcing makes these stones an appealing option to mined diamonds.
Lab-grown diamonds combine stunning looks and lower prices with ethical sourcing. This is making an impact on the diamond industry. Even De Beers, the world's largest diamond mining company, has started a lab-grown diamond line called Lightbox to meet this rising demand.
Younger buyers find synthetic diamonds especially appealing, and not just because of lower prices. These consumers have a greater awareness of the ethical and environmental problems that diamond mining can pose.
Amanda is a student of geological sciences and environmental studies at Tufts University. She grew up hiking and mountain biking in the Bay Area and continues to explore nature and learn about the beautiful gems and minerals it forms in her free time.
When you join the IGS community, you get trusted diamond & gemstone information when you need it.
Get started with the International Gem Society’s free guide to gemstone identification. Join our weekly newsletter & get a free copy of the Gem ID Checklist!