Ruby Gemstones Hardness 9.0. Ruby has been confused with red spinel and garnet . Other colors are known as sapphire .
Inclusions are common, and are used to tell the difference between a synthetic and natural stone.
Ruby is the birthstone of the month of July. Enhancements Ruby is usually heat treated to improve color and appearance. Surface cavities and fractures are commonly filled with a foreign material, including glass. As a by-product of heat treatment, the presence of solidified borax or similar colorless substances which are visible under 10x magnification are common. More information on gemstone enhancements.