The physical properties of SIAMITE® gemstone reflections (hardness 7.5-8, density 2.9-3.3 g/cm3, RI = 1.60-1.63) are optimally close to such natural gemstones as tourmaline, topaz, and emerald (see the attached Table 2). The quartz group (amethyst, citrine, smoky quartz, etc.) lags behind Siamite® in all three indicators, while corundum, spinel, and garnet have higher densities and refractive indices. Corundum surpasses Siamite® and all other gemstones in hardness.
It is known that many natural and synthetic crystals and glasses cannot be used for the "Setting Stones in Wax" method because they crack or change color under the influence of a high-temperature melt of gold, silver, bronze, or brass. Therefore, one of the most important advantages of SIAMITE® over other synthetic stones is its resistance to thermal shocks (Fig. 3). This is primarily determined by the low thermal expansion coefficient both in the crystalline phase and in the residual glass. In other words, during heating or cooling, the dimensions of the stones hardly change, and therefore, they do not crack or break.
Figure 3. Silver jewelry tree made by the lost wax casting process.
The second very important advantage of glass-ceramics is the uniformity and homogeneity of color. This is due to the nature of this material, its composition, and structure. In this sense, all types of glass-ceramics are similar to the original glasses because they are also uniform in color despite the complexity of their compositions. The subsequent crystallization of glasses and their transformation into glass ceramics does not disrupt the uniformity of color due to the even distribution of nanocrystals throughout the material volume.