Crystal eyeglasses punching is a thing of which era

Crystal eyeglasses perforated is a thing of the Song Dynasty. Legend has it that Zhu Zhishan, a great writer in the Ming Dynasty, used such glasses, and in the Song Dynasty, some people used crystal mirrors to cover the sun to improve their eyesight, which is the earliest origin of eyeglasses. Due to the exquisite craftsmanship and fine production, they were the top quality of eyeglasses at that time. It is worth mentioning that Liu Cui in the Northern Song Dynasty said in the "flawed diary" that Shi Hang of the Northern Song Dynasty had taken more than ten kinds of crystals to use when he broke the prison. Only later did we realize that he was because he could not see the handwriting on the paperwork, using crystals to look at. It can be seen that the Northern Song Dynasty has begun to use crystals to help improve eyesight.