Complex sentence: This method produced a dangerously high degree of long-term residual radioactivity and has been discontinued, although radium-treated green diamonds are still occasionally found in markets and can be detected by a Geiger counter or making its autoradiograph using a photographic film.
Split into simpler sentences: This method produced a dangerously high degree of long-term residual radioactivity and has been discontinued. However, radium-treated green diamonds are still occasionally found in markets and can be detected by a Geiger counter or making its autoradiograph using a photographic film.