On a varietal basis “Geuda” Corundum is one of the more recently appreciated members of the Corundum family. The term Geuda was initially used in Sri Lanka, to describe a property of translucency associated with milky or cloudy appearance seen in some Corundum gemstones. However with heat treatment of Geuda gemstones (a Corundum species) can be converted in to transparent sapphires. The most common Geuda varieties are Diesel Geuda, Milky Geuda, Silky Geuda, Dun Geuda, Ottu and Kowangu Pushparaga. The basic body colour in all these can be pale Blue, Yellow or Pink.
It is thought that of all the Corundum mined in Sri Lanka, about 35 to 40 percent could be categorized as treatable Geuda material in which the colours could be induced through heat treatment. The treatable Geuda Sapphires of Sri Lanka are proven to give better results than Geuda from other part of the world. Sri Lanka is blessed with a large supply of Geuda Sapphires suitable for heat treatment. These deposits are widely spread within the Island.
It is thought that of all the Corundum mined in Sri Lanka, about 35 to 40 percent could be categorized as treatable Geuda material in which the colours could be induced through heat treatment. The treatable Geuda Sapphires of Sri Lanka are proven to give better results than Geuda from other part of the world. Sri Lanka is blessed with a large supply of Geuda Sapphires suitable for heat treatment. These deposits are widely spread within the Island.