This seminar will add precious information to your basic gemological knowledge of rubies. You will learn about the natural characteristics of untreated rubies, the ruby treatments and the characteristics of each one (Thermal treatment, Thermal treatment with additives, cavity and fracture filling, diffusion, dying, oiling), synthetic overgrowth, and the methods of synthesis of rubies (melt and solution processes). This seminar is part of the advanced gemology series and is addressed to participants who are already familiar with the basic gemology of rubies.