Gemstones of Pakistan: Emerald, Ruby and Spinel
E. J. Gübelin, September 1, 1982
This article reports on three gem materials currently being mined in Pakistan.
Natural Rubies with Glass-Filled Cavities
Robert E. Kane, December 1, 1984
An examination and analysis of 15 natural rubies with glass-filled cavities.
Separating Natural and Synthetic Rubies on the Basis of Trace-Element Chemistry
Sam Mulhmeister, Emmanuel Fritsch, June 1, 1998
Natural and synthetic gem rubies can be separated on the basis of their trace-element chemistry.