The most basic marketing, which should not be taught, and the professional knowledge of jewelry. The most important thing is that you have to sell a lot of pieces, such as gold, pearls, jadeite, coral and diamonds. The door of jewelry can be said to be very deep. If it is jade, it is very deep. If there is no foundation, it can't be sold at all. The required professional knowledge is very strong, and jade can't be learned all one's life. You should be prepared. If you sell other things, it will be deep.