The diamond ring of the future will radiate its unique beauty-quite literally-thanks to a minuscule radio-frequency identification (RFID) chip embedded in it. Scientists at Hitachi Research Labs in Japan have devised the smallest RFID tag ever, just 0.05 millimeter by 0.05 millimeter, tinier than a grain of sand. The so-called powder chip is thin enough that it can be mixed with paper pulp to add a layer of counterfeit protection to gift certificates, passports and currency.