As follows from the part 5, the SIAMITE® completely replicate the brightness, color, and density of the most widely used gemstones. In connection with this, a common question arises – how to distinguish faceted SIAMITE® stones from natural gemstones? This question is quite relevant, as many buyers of our stones have already turned to gemological laboratories in many countries worldwide and received incorrect conclusions – “glass”, “special glass”, “natural tourmaline”, “topaz” …
Gemologists worldwide have a standard set of criteria for identifying gemstones: color, refractive index, density, magnification, absorption spectrum, fluorescence. However, the nature of SIAMITE® glass-ceramic makes classic gemological techniques less valuable or even useless. How to diagnose that SIAMITE® is a glass-ceramic material, not glass or a natural stone? This can be definitively done only through X-Ray diffraction analysis (XRD) (Fig.10).
Figure 10. X-ray diffraction pattern of Emerald Green SIAMITE®, confirming the presence of nanocrystals of spinel, rutile, and zirconium titanate (analyzed in MTEC, Thailand).
XRD is the only laboratory technique that non-destructively and accurately obtains information, such as phase composition, crystal structure, and crystallite size of powder, solid, and liquid samples. In an X-ray diffractometer, different crystal phases yield distinct diffraction patterns. Phase identification can be performed by comparing patterns obtained from unknown samples to those in reference databases (ICDD - International Center of Diffraction Data). This process is akin to matching fingerprints in a crime investigation.
Glass – by definition, cannot contain any crystalline phases, even if it is "special," optical, or from prestigious brands. The distinction between SIAMITE® and glass is well illustrated in the attached Figure 10 – the X-ray diffraction pattern of glass forms a smooth line, while in the emerald-like SIAMITE®, peaks of zinc spinel (gahnite), zirconium titanite, and others are clearly visible.
Naturally, this analysis reveals that SIAMITE® is not the natural mineral it imitates. X-ray phase analysis is the most accurate and reliable tool for diagnosing any crystalline phase, from nano-sized to large crystals, natural and man-made. In our opinion, it should be included in the existing set of gemological methods for diagnosing gemstones and materials.