Lin's five-year repurchase is the diamond purchased by Party A's customers with gold and platinum. This agreement can only enjoy five years of security and restoration services. After Party A requests to buy back the diamonds, it shall keep the diamonds in good condition and provide sales documents, original vouchers and ID cards. Value preservation refers to a commodity or asset that will not be affected by financial problems, and its specific super-realized value or a commodity that can increase in price with the development of society.