The technology of synthesizing sapphire glass was invented in the 19th century and has been applied to watches since the 1960s. The sapphire mirror installed on the watch is actually made of aluminum oxide, which removes impurities such as iron oxide and titanium oxide. From a chemical perspective, synthetic sapphire is no different from sapphire. Since no other elements have been added, it is colorless and transparent, without a "blue" color. Synthetic sapphire is made from unprocessed alumina at high temperatures, then cut into disks using diamond tools and polished into lenses. The high cost of processing tools is also one of the reasons for the high cost of sapphire watches.

Sapphire glass, as an excellent optical product, has good transmittance in the ultraviolet, infrared, and visible light bands, which can meet the requirements of multi-mode composite guidance. It also has excellent mechanical properties, chemical stability, and high temperature resistance, making it an ideal multispectral broadband window material. Compared with ordinary broadband window materials, it has many excellent mechanical and optical properties, suitable for laser instruments, optoelectronic devices, window materials, etc. The infrared transmittance of the silicon dioxide film on the sapphire substrate is significantly improved, and the silicon dioxide film still has good anti reflection effect at high temperatures. After being eroded by rainwater, the average transmittance of coated sapphire samples is significantly higher than that of uncoated sapphire samples. After testing, the average transmittance loss of the coated sapphire sample was minimal, and the infrared transmittance of the coated sapphire was significantly higher compared to the uncoated sapphire.

Sapphire has a hard texture and will not be scratched. Whether natural or synthetic, it is a hard material with a Mohs hardness of up to 9, which makes sapphire difficult to scratch. However, some substances such as artificial silicon carbide compounds with a hardness of 9 can also scratch sapphire. If there is friction between these materials, scratches may be left on them. In terms of preparation, sapphire glass can be used to make lenses, and the finished product has the same performance as the lens.