Coated Pink Synthetic Moissanite
The French Gemmological Laboratory (LFG) recently received a 0.41 ct pink stone resembling a pink diamond (figure 1) for identification. The surface of the stone showed numerous patches (figure 2), casting doubts about the natural origin of its color.
Under the microscope, these flakes showed metallic luster. Furthermore, the pink color appeared concentrated at the surface. Some unevenness in the color was observed due to scratches of this film. When observed through the crown, the gem showed a clear doubling of its edges, indicating an anisotropic material. These observations confirmed the client’s doubts that the gem was a pink diamond (figure 3).
The sample was analyzed using infrared, UV-visible, and Raman spectrometers. All the spectra collected indicated a synthetic moissanite coated with a colored film. Chemical study of this film acquired with an EDXRF spectrometer revealed that iron and titanium were responsible for the color of the calcium-rich film.
This is the first example the LFG has seen of synthetic moissanite coated with a thin colored film. This type of treatment is not rare with topaz, quartz, diamond, or tanzanite. Gemologists must remain vigilant because this treatment can be performed on all gems, natural or synthetic.
