How Does Beryllium Diffusion Change Sapphires?
Diffusion processes, including both titanium and beryllium treatments, are relatively new techniques that have generated a great deal of controversy in the marketplace. Although diffusion procedures have several variations, sapphires are typically heated to very near their melting point in the presence of color-inducing elements, which penetrate or diffuse into the stones. In the case of titanium diffusion, a layer of strong color is created near the surface of a poorly colored stone. Since the layer of color is surface level only, the original weak color of the stone can be revealed if it is chipped, nicked or re-polished.
Newer diffusion techniques use the element beryllium, which has a smaller atomic structure than titanium, so it is capable of penetrating deeper into the sapphire. While titanium colors pale sapphires blue, beryllium is most often used to induce orange or golden hues.
During the 1990s, the treatment was hard to detect, since the coloring agent penetrated deeply and uniformly into the stone. As a result, many of these treated sapphires were mistaken for natural Padparadschas.
Diffusion treatment is often the last resort when heat treatments have failed to enhance the color of a stone. Sapphires that have obtained their color from diffusion treatments have little intrinsic value. Reputable dealers will identify diffusion-treated sapphires and offer them at prices well below those of natural, untreated stones. The final treatment to learn about is Irradiation, this process is not often done since it does not achieve permanent results.