Probe into Colour Grading of Blue Sapphire

Colour is the most important standard in grading of coloured stone. The aim of this paper is to carry out the colour grading of the blue sapphires from the famous localities in the world according to their values of H, S, B determined by means of Photoshop Microsoft. The influence factors on the colour grading and the problems are discussed and the proposals how to resolve these problems are also put forward.