The explanation upstairs is correct, but I want to add that the price of gold is closely related to its purity. Purity is the amount of impurities contained in one gram of gold. For example, pure gold is 990, which means that there are only 99 grams of gold in 100 grams of gold, and one gram is an impurity. It is 990,999, which is what we call thousands of gold. Because there is no provision in the national trademark law, the state will not mention it for the time being. The price can refer to the daily gold futures price, which can be found in SOSO! Finally, the pure gold you mentioned at the beginning doesn't exist, but I guess it's because jewelry is made of "thousand" pure gold, and the top of the thousand words has worn off! Turned into pure gold! Gold wears away easily! Its hardness is only the same as human nails, both of which are 2.5!