(1) Kim cương: mainly produced in Yimeng Mountain, Shandong and Dalian, Liaoning. Trong số đó, the quality of gem-grade diamonds from Dalian Wafangdian is the best. (2) Sapphire: mainly distributed in the eastern coastal areas, such as Hainan, Fujian, Jiangsu, Shandong and Heilongjiang provinces. The storage capacity is considerable, but the color is mostly indigo blue with […]
