The ceremony, held on a campus lawn in Heilongjiang province, drew the largest turnout in the event’s history, according to Xinhua. Since the tradition began in 2013, 803 couples have married through it, Sixth Tone reported, and for the past two years each pair has gone home with a ring bearing a one-carat diamond the team calls “Sincerity,” China Daily reported.
The diamonds come from the Infrared Thin Films and Crystals team at HIT’s School of Astronautics, led by professor Zhu Jiaqi. Over years of work the team built high-power microwave plasma chemical vapor deposition (MPCVD) equipment and a method for growing high-quality single-crystal diamond efficiently. Zhu likened the process to assembling a structure block by block at the micron scale, Xinhua reported.
The method is deceptively simple. Technicians mix methane with hydrogen and feed the gases into a reaction chamber, where they act as a kind of nutrient solution. Microwave plasma excites the molecules, which break into reactive atomic groups, and carbon atoms settle layer by layer onto a seed crystal to form pure single-crystal diamond. The rough stone is then cut, polished and set. How fast a one-carat stone grows depends on the method and gas density, but a high-quality diamond typically thickens by only a few microns an hour.
Normally, a natural diamond takes hundreds of millions of years to form under crushing heat and pressure deep underground. The stones HIT handed its newlyweds went from “seed” to finished gem in a matter of days, Xinhua reported.
Newlywed couples at the mass wedding for PhD holders and doctoral candidates at Harbin Institute of Technology on May 31. Photo courtesy of the Harbin Institute of Technology |
What makes the gesture possible is how thoroughly China now dominates the industry. Global production capacity for lab-grown rough diamonds stands at about 40 million carats, with China accounting for roughly 63%, or about 25.2 million carats, according to the 2025 Lab-Grown Diamond Industry Development Report released in Zhengzhou in December and reported by China News Service. The country’s lab-grown diamond market is worth around 14 billion yuan ($2.1 billion), about 11% of the global total, and is projected to top 102.5 billion yuan ($15 billion) by 2030.
That scale has collapsed prices. A 1-carat high-quality lab-grown diamond was quoted at 1,800 to 3,500 yuan ($265 to $515) at Shenzhen’s Shuibei wholesale jewelry market, down from around 8,000 yuan in 2020, the 21st Century Business Herald reported, a fraction of what a comparable mined stone fetches. The same technology that lowers the price of a wedding ring also feeds higher-end uses such as chip thermal management and quantum sensors, the report noted.
HIT has led China in artificial crystal growth for decades. In 2004 it produced what was then the country’s largest lab-grown sapphire, measuring 29 cm across and weighing 30 kg. The diamond technology behind the wedding rings has since won a national technology invention award, Xinhua reported.
At the ceremony, Zhu offered his blessing to the couples, telling them that just as scientific research demands the courage to overcome challenges, married life calls for the patience to tolerate and understand one another, Sixth Tone reported.
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