(1) Laboratory method: It is very similar to jewelry appraisal, and all the instruments and equipment used are the same. The most commonly used instrument for jewelry identification is refractometer, which can measure the refractive index of the detected object. Although sapphire watch glass is artificial, its refractive index is 1.76~ 1.77, just like natural glass. Because sapphire glass is crystal, the refractive index is very heavy, which is 0.008. When testing, you can see it clearly by rotating the polarizer on the eyepiece. Flat glass is best observed, spherical glass is not very beautiful, so refractive oil should be coated when testing. The refractive index of mineral glass is about 1.52, which is easy to distinguish from sapphire. It has no birefringence. Another method is to use a polarizer, and all crystals can be detected with a polarizer, such as crystals. Sapphire is also a crystal. When the polarizer is rotated, the light will change alternately with a period of 90 degrees. However, if you use a polarizer to check the watch glass, you must take out the whole movement and expose the watch glass. But some non-sapphire watch glasses may also have polarizing effect, because they are also made into crystals, such as crystals. There are more watches in Japan.

(2) Look at the logo of the watch and the hardness of the glass: If it is a regular brand watch, sapphire glass is usually printed on the back cover of the watch, which is expressed by English sapphire or sapphire crystal. Nowadays, it is very common to use sapphire watch glass even if it is a fake watch or a counterfeit watch. To test the hardness of the watch glass, you can use a sharp metal object like a needle to draw the most inappropriate eye on the edge of the watch glass. It feels hard, and there is a feeling that metal objects are floating over. There are no scratches on the glass. It should be sapphire glass.