When Harbin Institute of Technology (HIT) held its 11th group wedding for doctoral students on May 31, each of the 187 newlywed couples was presented with a one-carat diamond ring, with the diamonds grown in the university’s laboratory. The gems were developed by Zhu Jiaqi and his team from HIT’s School of Astronautics using a technology that in theory could produce high-purity, single crystal diamonds of any shape and size – from wedding jewellery to a wafer as wide as a basketball. Known as...