(1) Kim cương: mainly produced in Yimeng Mountain, Shandong and Dalian, Liêu Ninh. 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, Phúc Kiến, Giang Tô, Shandong and Heilongjiang provinces. The storage capacity is considerable, but the color is mostly indigo blue with [...]
