Abstract

Currently, high quality ruby and sapphire deposits of Việt Nam are found in Yên Bái (Lục Yên district) and Nghệ An (Quỳ Châu and Quỳ Hợp) provinces. Dark color sapphire with large reserves is being extracted in the Central Highland provinces such as Gia Lai, Dak Lak and Lâm Đồng. Sapphire is also extracted in Đồng Nai and Bình Thuận provinces. Besides, ruby and sapphire have lower reserves and quality are also extracted in Quảng Nam. By studying and comparing ruby and sapphire from different deposits in terms of gemological and chemical characteristics, one can identify typical characteristics of each deposit and differentiate their geographical origins. Sapphire from Central Highland, southern provinces and from Quang Nam provinces have low gem quality in comparison to the samples from Yên Bái and Nghệ An. The averaged amount of Fe in Central Highland sapphire is considerably higher than all other areas. We can separate between ruby from Nghệ An and ruby from Yên Bái by the ratios of coloring elements Fe2Ơ3/Cr203 and Ticyc^ch. Even in some cases, ruby from different deposits in Yên Bái can be distinguished by the concentration of Cr and Fe.