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.
