A simple way to distinguish toughened glass from ordinary glass:
2.1 With polarized sunglasses, you can see the color markings, which should not be seen without tempering.
2.2 Turn the angle to see if there are any pressure spots on the glass surface. You will see the irregular deformation of the whole glass surface.
2.3 Look at the side, when glass tempered, it will soften, flatness will become worse because of the roller, face to face, the gap in the middle is an ellipse, so it is obvious.
2.4 The flatness of tempered glass is worse than that of ordinary glass. A simple way is to put two pieces of glass face-to-face vertically close together, observe the two long sides of two pieces of glass adjacent to each other, and see if there are any obvious gaps between the two long sides of glass. If there are gaps, whether they are all curved or not, it should be tempered. It's face-to-face, not back-to-face. It's physical strength. Otherwise, when you look at the side with two exposed X-ray films at 70 degrees, you should see the tempered blue wind spots. The flatness of the glass is also significantly lower than that of the glass before tempering.