Rubies from Mong Hsu

Today, the primary source of commercial quality ruby  material is from the Mong Hsu region of Myanmar (Burma).   The ruby material from this region is typically zoned with blue areas and filled with surface fissures.  This material is treated to make it marketable.

This process includes heating the material in a controlled environment.  

David Felderman, in an article entitled Red Baiting in Modern Jeweler states, "that heating was necessary to "heal" these tiny opening and turn stones from opaque pebbles to semi-transparent gems suitable for jewelry. By healing, we mean the use of chemical compounds such as borax that act as catalysts to help melt the walls of fissures into liquid ruby that recrystallizes in solid form as the heated gem cools and closes the fissure."

The flux residue is sometimes found in  healed fissures.  The finest of these gemstone are a bright red.  The stones typically have a cloudy appearance. These stones rarely exhibit the characteristics more typical of the Mogok region.