Need. When customers buy diamonds, merchants need to issue payment bills, quality guarantees and diamond identification certificates. So Tianhe City bought diamonds and issued invoices. Diamond refers to polished diamond, which is a natural mineral and the original stone of diamond. Simply put, diamond is a simple crystal composed of carbon element formed under high pressure and high temperature conditions in the deep part of the earth. On May 17 and 16, Sotheby's held a spring jewelry auction in Geneva, Switzerland. A pair of colored pear-shaped diamond earrings sold for $57.4 million, or about RMB 395 million, setting a new record in auction history. This pair of pear-shaped earrings is made in South Africa. Except for the different colors, the appearance is almost the same, weighing about 16 carats respectively. Among them, the dark pink diamond was named "Artemis", which earned US$ 6,543.8+0.55 million (RMB 654.38+0.067 million), and the other diamond was named "Apollo" because of its rare color, which was more than twice as expensive as the pink diamond.