It was not until 1800 that Ruby was recognized as being a corundum species as well as Sapphire. Before that red stones like garnet and spinel were all called "Rubies."
Ruby is one of the most expensive gemstones always related to wealth and prosperity. Larger carat weight Rubies can even be more costlier than Diamond.
Colors of Ruby can range from purplish, pinkish and orangish red. The "pigeon blood red" is the most sought after color. Chromium is the mineral substance that gives Ruby its color.
Ruby is a very durable and wearable gemstone. Ruby is next to Diamond for hardness being 9 on the Mohs scale. A Ruby's luster is almost diamond-like, the red color glows from within.
Large quality Rubies are extremely valuable and rare. There is also a cabochon cut ruby the Star Ruby, having a 6 rayed star.
Inclusions in Rubies are quite common, they are a Type II gemstone, (GIA grading system - Type II gems usually shows some type of inclusion.) Remember inclusions are what tells us the gemstone is natural, not a synthetic.
Majority of Rubies have had some type of treatment, cavity filling, radiation, heating. This just enhances the beauty of the gemstone. Rubies are generally stable for cleaning purposes, careful with the ultra sound and steam cleaning. Warm soapy water is always a good choice for cleaning your gemstones.