Diamond may be the hardest naturally occurring material on Earth, but admire a sparkler in unfiltered sunlight, and it will start shedding atoms. The discovery shows that diamond can be etched gently instead of through the more damaging process of laser ablation for use in high-performance lasers and more efficient optical devices. “Although this type of light-induced evaporation has been observed in some materials, this is the first time it’s been shown to occur for diamond,” said Richard Mildren, associate professor at Macquarie University Photonics Research Center. The diamonds were exposed to intense light pulses in the UV-C band — the harsh rays filtered out by the ozone layer — and small pits in the diamond surface were visible after only a few seconds. The rate of mass loss in the diamond fell notably for lower light levels, but the etching process still continued — albeit at a slower and slower pace, he said. Evaporation of diamond induced by an ultraviolet laser beam. (Image: Richard Mildren) But before diamond lovers around the world start to panic, he is quick to note that the rate of evaporation is very small and not noticeable under normal conditions. In fact, even under very bright UV conditions, such as intense sunlight or under a UV tanning lamp, it would take approximately the age of the universe — about 10 billion years — to see an observable difference, he said. The findings not only provide clues about the long-term stability of diamonds, but also have broad implications for future research. “It’s a very practical discovery, and we are now looking at how we can exploit this,” Mildren said. “If we can make structures in the diamonds that enable us to control the position of the light within a very narrow filament in the diamond, that’s the first step to making smaller and more efficient optical devices such as those used in quantum computing and high-performance lasers.” The discovery also may have implications as far-reaching as the prospects for finding diamonds on the surface of other planets, Mildren said. The study was published in the journal Optical Materials Express. For more information, visit: www.mq.edu.au