In the currency history of China, gold and silver were officially called "gold ingots", which began in the Yuan Dynasty. However, as early as the early Tang Dynasty, in the Kaiyuan Bao Tong period, people regarded it as huge and valuable, and read it as "opening an ingot". In the Yuan Dynasty, gold and silver coins were called "gold ingots", which means the treasures of the Yuan Dynasty. Gold is called gold ingot and silver is called silver ingot, which is not only of political significance, but also the common name of gold and silver currency.
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Maintenance method
Besides red and black spots, gold products sometimes have white spots, especially gold jewelry. This is mainly because consumers tend to put gold ornaments in drawers at will, and once they encounter mercury, they will immediately form a large area of white spots.
Especially when women use cosmetics containing mercury, long-term contact with gold products will also produce white spots. If you wear platinum and silver jewelry, white spots will also appear on the surface after long-term friction.