WASHINGTON, Nov. 17 (Agencies) – A team of American researchers has discovered a method to mass produce inexpensive perfect diamonds of any dimension in laboratories.
Led by Russell Hemley of the Carnegie Institute of Washington, the team produces diamond crystals by laying carbon atoms of a gas on a surface.
The chemical vapor deposition (CVD) accelerates the diamond's growth rate, but lets the impurities from the gas into the diamonds, giving them a brownish tint.
Although annealing, a costly high-pressure, high-temperature treatment, can purify diamonds, only relatively small ones can be produced this way.
Researchers have overcome size limit by 'cooking' their diamonds in low-pressure hydrogen plasma in microwave at 2200 °C. The only criterion to limit diamond size is now the size of the microwave chamber used.
"The most exciting aspect of this new annealing process is the unlimited size of the crystals that can be treated. The breakthrough will allow us to push to kilocarat diamonds of high optical quality," says Hemley's Carnegie Institute colleague Ho-kwang Mao.
"The microwave unit is also significantly less expensive than a large high-pressure apparatus," adds another team member, Yufei Meng.
According to Meng, the method can help produce diamonds with fewer impurities than natural ones. "We once sent one of our lab-grown diamonds for jewelry identification, it wasn't told apart from natural ones," she said.
These high quality synthetic diamonds are now threatening the natural diamond market forcing some companies to sell synthetic diamonds as gemstones.
Synthetic diamonds can be used in high-end technologies and making ultra-high quality windows, optically transparent to lasers.
