South Korean Scientists Develop a Fast and Affordable Method to Produce Diamonds

A view of the main 51.38-carat round-cut diamond, the Dynasty, among other gems from Russian diamond miner Alrosas Dynasty polished diamonds collection in Moscow on Aug. 3, 2017. ( Yuri Kadobnov/AFP via Getty Images)

South Korean scientists say they have developed a new method that creates high-quality synthetic diamonds in just three hours.

Scientists from South Korea’s Institute for Basic Science (IBS) published a study in the scientific journal Nature at the end of April about the development of a method involving liquid metal in a graphite crucible with methane (CH4) and hydrogen gas (H2) at 1,025 degrees Celsius (1,877 Fahrenheit) and atmospheric pressure to produce diamond crystals. The study garnered 14,000 views and coverage from nearly 70 media outlets, ranking highly in scientific reports.

This innovative approach utilizes a liquid metal mixture of gallium, iron, nickel, and silicon to catalytically activate and diffuse carbon atoms, forming diamonds at the interface with the graphite crucible, significantly lowering the pressure and temperature requirements compared to traditional high-pressure, high-temperature (HPHT) diamond synthesis.

Although the produced diamond crystals are no larger than 100 nanometers in diameter, the resulting diamond films can be cleaned of surface metals with hydrochloric acid solution and transferred anywhere.

These crystals and films are of particular interest in advanced electronics and optics, as previous diamond film production required expensive equipment. The new method significantly reduces production and transfer costs.

Diamonds are among the hardest materials on Earth, possessing the highest atomic density and thermal conductivity, with a Brinell hardness number of approximately 45,000 BHN, density of 3500 kg/m3 (219.37185 lb/ft³), and a thermal conductivity of about 1000 W/(m·K).

However, the scarcity and high cost of natural diamonds present challenges. According to Statista, the annual demand for diamonds is around 292 million carats (about 64.4 tons), natural diamond mining cannot meet this demand, necessitating the use of synthetic diamonds.

In 2022, the global production of natural diamonds was almost 121.5 million carats (about 26 tons) worth almost $16.3 billion, according to Kimberley Process statistics.

Currently, a high-clarity, colorless, two-carat round-cut natural diamond can cost around $16,000, whereas a lab-grown diamond of similar specifications costs about $2,600, according to The Diamond Pro.

Natural diamonds are composed of a three-dimensional carbon atom structure with a strict arrangement that allows few impurities to enter. When elements like nitrogen (N), silicon (Si), or other impurities are present, they can give the diamond different colors.

For example, boron results in blue diamonds, nitrogen results in yellow, defects lead to brown, and exposure to radiation can create green diamonds. Additionally, natural diamonds can appear in rare colors such as purple, pink, orange, and red, which are more valuable than ordinary diamonds.

Scientists believe natural diamonds form under temperatures of 900 degrees Celsius (1,652 Fahrenheit) to 1,400 degrees Celsius (2,552 Fahrenheit) and pressures of 5 to 6 Gigapascal, though the formation time is not fixed due to the non-continuous nature of the process.

Artificial diamonds are typically synthesized through two methods, capable of producing centimeter-scale or larger diamonds. The first method, chemical vapor deposition (CVD), generates diamonds from hydrocarbon gas mixtures, often using materials like zirconium oxide and silicon carbide.

The second method, high-pressure high temperature (HPHT), was first utilized by General Electric scientists in 1955 to synthesize diamonds at 7 GPa and 1,600 degrees Celsius (2,812 Fahrenheit), producing cubic centimeter-sized single-crystal diamonds in 5 to 12 days. Despite becoming mainstream, the size of HPHT diamonds is often limited, prompting scientists to explore alternatives under milder conditions.

In 2016, lab-grown diamonds accounted for only 1.7 percent of global diamond sales, but this share has been increasing, with estimates suggesting it may represent 10 percent by 2030, according to Statista.