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Corundum is a natural material that is second only to diamond in hardness. It is only diamond that has to be ground into such a fine granule. In order to verify this conclusion, the researchers also used diamond, silica, quartz sand, three modern abrasives to polish the raw materials of jade, and used the atomic force microscope to observe the surface of the jade axe and the surface of the jade raw materials they processed. It was found that only diamond was used. Polished jade raw materials, the surface can best match the surface of jade axe unearthed in China. Even so, the jade that is processed by modern industrial methods still has a surface that is not as refined as the products of Chinese artisans 6,000 years ago.
Lu Shuyi guessed that prehistoric Chinese artisans discovered diamonds as the best material for polishing jade surfaces after countless trials and countless failures, while corundum was used to "roughing" jade articles. There is a diamond mine in the north of Jiangsu and the south of Shandong, about 300 kilometers away from the Liangzhu Cultural Site and the Sanxingcun Cultural Site, which provides a reasonable basis for their views.
But unfortunately, the discovery of prehistoric craftsmen did not spread well in China. Lu Shuyi said that prehistoric craftsmen can only impart experience through personal contact, and they can record their experiences without words. It is known that the earliest era of written records in China was the Shang Dynasty nearly 4,000 years ago. Liangzhu culture and so on are likely to have no direct connection with the Shang Dynasty, so it is impossible to record the knowledge of diamonds. The record of diamonds in Chinese history is already in the Song Dynasty.
Lu Shuyi is born in the United States and his mother is from Hong Kong, China. He studied under Princeton University and is pursuing a Ph.D. in physics at Harvard University. Lu Shuyi has a keen interest in Chinese history while studying physics. He is eager to understand Chinese history and culture that has a connection with himself, and hopes to use his physics background to contribute to the study of Chinese history. In 2004, he published a paper in the journal Science, confirming that China invented duplex machinery earlier than the West.
Why is the surface of the exquisite Chinese prehistoric jade so smooth? Lu Shuyi, a Chinese-American researcher at Harvard University, found that as early as 6,000 years ago in the Neolithic Age, Chinese ancestors used diamonds and corundum to process jade ornaments. Researchers have used modern physical methods to prove that Chinese people used diamonds and corundum at the earliest, and the skills they once mastered were difficult to achieve with modern processing methods. The research results of Lu Shuyi and others are published in the Journal of History. This achievement has pushed the history of human use of diamonds for thousands of years. Previously, the scientific community had believed that humans used diamonds no earlier than 500 BC. In the first century AD, the ancient Roman writer Pliny first recorded the substance that might be diamond. Â Lu Shuyi and others studied four jade axe ornaments, which were excavated from the Liangzhu Cultural Site in Zhejiang, China and the Sanxing Village Cultural Site in Jiangsu. The older three were about 4,000 BC to 3500 BC. One of the more "new" ones was unearthed in the late Liangzhu Cultural Site, dating back to about 2500 BC. The researchers used X-ray diffraction, electron microneedle and electronic scanning mirrors to detect the surface of the jade axe. The surface of the jade axe contained up to 40% of the finely divided corundum.