Nanogem or Nanocrystal®, which is another patented name of the same material, refers to a class of transparent glass-ceramics. Nanogems chemically are the high-temperature alumosilicates (the chemical composition is a mixture of oxides: SiO2, Al2O3, MgO, Li2O,…). This so-called hybrid material is composed of nanosized (about 10ˉ⁹ mm in dimensions) crystals of spinel, sapphirine, cordierite, garnet, quartz and other crystals that are homogeneously distributed in the amorphous matrix. These crystals also occur in nature and can therefore be called created nanosized crystals of naturally existing gemstones – Nanocrystals®, Nanogems or Nanogemstones. The analogue of the glass-ceramics in nature is obsidian, an effusive volcanic rock composed mainly of natural volcanic glass with abundant nucleation crystals (crystallites) and microlites.