The vast majority of these items from China are not natural material but are glass, either molded or molded and cut.  Unfortunately, like so many mis identified pieces from China, they prey on the ignorance of buyers who believe they are buying a natural material but in reality are buying a piece of cheap costume jewelry.   The variety of colors and subject matters such as phoenix and dragon should immediately draw the buyers attention, too many of one item is a strong indication that it is a man made item.  I have over 35 years experience buying and selling estate jewelry and fine Asian antiques and work for a nationally recognized company specializing in the same merchandise.