Early in the 19th century, attempts to give diamonds some color were pretty coarse, basically involving using vegetable dyes and ink to coat the stones. But these coatings were not permanent. The breakthrough in color enhancement came in 1905 when an English chemist Sir William Crookes permanently changed the color of diamonds by exposing them to radiation. He did this by burying some diamonds in radium – bromide salts for an extended period of time. This permanently changed the color of those diamonds on the surface to different hues of blue and green. However, there was a problem – the stones were dangerously radioactive after the process, and obviously, completely unusable. Nevertheless Sir William Crookes proved that diamonds could be irradiated to change their color, and the search was on to find the safe means of doing so.