开发深色蓝宝石新构思朱而勤山东昌乐的蓝宝石以颗粒大、裂隙少、成品率高为重要特点，而且品种多，其中的普通蓝宝石和特异蓝宝石已得到广泛利用。在宝石级（可磨制各种刻面、素面饰品）和不能用作宝石的刚玉之间，还存在着大量的过渡品。这些过渡类型以颜色深暗、透明度... Development of a new concept of dark sapphires Zhu and Qin Shandong Changle sapphire particles to large, less cracks, high yield as an important feature, and many varieties, of which the ordinary sapphire and sapphire have been widely used. There is also a large number of transitional products between the gems (various facets and plain ornaments) and the corundums that can not be used as precious stones. These transitional types are dark in color, transparent ...