Amber from the Thanbaya Gaing Coal Mine, Minbu Township, Magwe Region, Myanmar

Determining the geographic origin of yellow sapphires plays a critical role in the gem trade, as ori

Yuri Shelementyev, Galina Kriulina, Olga Yarapova, Viktor Vins, and Alexander Stolyarevich

In recent years, an increasing number of sources of fei cui, such as Guatemala, Italy and Russia, ha