Corundum Gemstones can be treated in several ways to enhance its beauty, fracture filling being the most common treatment which is done using epoxy resin, oil, wax and glass as fillers, this reduces flaw visibility by making the fractures non reflective. Heating is another treatment done on Corundum gemstones. This lighten or intensifies the color of the gem and increase its clarity by melting some of the inclusions commonly known as "silk" which are a common occurrence in Sapphires. Diffusion treatment is the third method and is only used to color the surface of the stone while the centre of the gem remains colorless, this is a permanent treatment unlike irradiation which will fade and is therefore not an accepted method of enhancing the Sapphire. Diffusion treatment can be used to produce a six ray star effect.
