Radioactive Residue (7.34)
All three of these irradiation methods do not leave any detectable radioactive residue in the stone after treatment. This was not always true. Shortly after Marie Curie discovered Radium and Polonium in 1898, Sir William Crookes exposed colorless diamond crystals to radium compounds for approximately one year. Although the experiment was a success, the dark green-colored hue it left was very shallow, and the treated diamonds were made radioactive. The radioactivity was dangerous, but it is believed that most of these stones have been removed from circulation.
The first significant tests on how radiation affects diamonds had been carried out by Sir William Crookes, an English physicist and chemist.
Method: Crookes buried diamonds for a prolonged time—78 days for an instance—in the radium-bromide salts. When radium became known in 1898, it was a potent and newly discovered source of radiation.
Results: The diamonds' atomic structure was permanently changed by the radiation, turning them a dark green. But the diamonds themselves became extremely radioactive and unsuitable to wear and the color was often blotchy and just penetrated the surface.
Legacy: One of these radioactive diamonds was given to the British Museum by Crookes in 1914, and it is still present today. His tests shown that radiation may permanently alter a diamond's hue, which prompted more investigation into safer approaches.
Endowment: One of these radioactive diamonds was given to the British Museum by Crookes in 1914, and it is still there today. His tests shown that radiation may permanently alter a diamond's hue, which prompted more investigation into safer techniques.
The above image is courtesy of: https://en.wikipedia.org/wiki/William_Crookes