Micro-World Gems & Gemology, Winter 2021, Vol. 57, No. 4

Radioactive Green Diamond

A 2.42 ct green diamond treated by radioactive salts.
Figure 1. Green diamond treated with radioactive salts. Photo by Diego Sanchez.

The rarity of naturally colored green diamonds has created the demand for artificially irradiated green diamonds. One 2.42 ct green diamond recently examined by the author showed signs of radiation treatment by the use of radioactive salts (figure 1).

A telltale mottled green appearance could be seen.
Figure 2. A mottled green appearance was visible on the table facet of the green diamond treated with radioactive salts. Photomicrograph by Nathan Renfro; field of view 4.70 mm.

Microscopic analysis revealed telltale green mottled and shallow radiation stains over large areas of the stone, causing its green bodycolor (figure 2). These radiation stains were produced by exposing a cut and polished diamond to radioactive salts for an extended period. The inert to ultraviolet light radiation stains were easily visible against the diamond’s blue fluorescence seen in the DiamondView (figure 3).

The radiation stains are inert to ultraviolet light.
Figure 3. This diamond’s blue fluorescence provides strong contrast to the inert radiation stains, as shown by the DiamondView. Image by Michaela Stephan; field of view 8.265 mm.

Treatment using radioactive salts (such as radium) is not often used anymore, as this method may produce dangerously radioactive diamonds. Today, most artificially irradiated diamonds are treated with a low-energy electron beam (Spring 2013 Lab Notes, pp. 46–47). When tested with a Geiger counter, this stone was revealed to be weakly radioactive.

Michaela Stephan is a staff gemologist at GIA in Carlsbad, California.