Zhou Shengsheng, Chow Tai Fook, Luk Fook Jewellery and Laomiao Gold all said that "trade-in" must be charged a depreciation fee, which includes not only the loss of remelting and recasting, but also the working hours of remelting. At present, there is no unified industry standard for depreciation and working hours in China, and each brand dealer independently formulates relevant standards. Because many merchants do not support the exchange of platinum for gold, take the exchange of gold for gold as an example. Zhou Shengsheng, Chow Tai Fook and Luk Fook jewelry are all calculated according to the depreciation expense of "trade-in" of 30 yuan/gram, and the weight of the replaced gold ornaments is heavier than the original gold ornaments, while the working hours of the new gold ornaments are calculated according to the full weight. However, the depreciation expense of gold ornaments of Old Temple Gold is 25 yuan/gram, and the part of the purchased gold ornaments whose weight is higher than that of the original gold ornaments is counted as working hours.