Rubies have been sought after since ancient times because of their lively red color. Almost all rubies have been heat treated to lighten or intensify color, or to try and improve clarity. Since about 2001 many African rubies have been treated with Beryllium diffusion to improve color. This treatment is not effective with Burmese rubies, so at this time it can be assumed that rubies with inclusions indicating Burmese origin are not treated with Beryllium. About 2006 the market was flooded with African rubies which were glass-filled to varying degrees. Some of these contained so much glass that they were essentially composite stones. As with diamonds, glass filled rubies need to be identified so bench jewelers can handle them with more care. More recently, there has been a good supply of rubies from Africa that are an excellent red color with no treatments - not even heat treating! This is a very encouraging development, especially with the relative scarcity of Burmese rubies, and the ban on their importation to the US.
Treatments: Heat treating is almost universal, Beryllium diffusion in African rubies, and fracture filling.