Effect of Colouring Element of Ruby from Different Localities on Its Colour Characterization

Due to different content of colouring element, the colour characterization of ruby from different localities is different. In this paper, the “locality” is one of indicators to evaluate quality of ruby on the market. Therefore, the authors selected three kinds of rubies with locality characteristics (Burma, Mozambique, Africa) as samples. By using X-ray fluorescence spectrometer, UV-visible-near infrared spectrometer, the trace elements and colour of the ruby samples were measured. On the basis of colorimetry, the ruby samples were classified and compared. The results were: (1) The trace elements of Burmese ruby present “Rich Cr poor Fe”, whose fluorescence is strong, and colour is purple red；(2) The Cr contents of Mozambique and Burmese rubies are similar, but the former has a certain content of Fe, and its purple tone becomes weaker, as well as the lightness and chroma value decrease. The Mozambique ruby is dark red; (3) The trace elements of African ruby present “Rich Fe and poor Cr”, with very weak fluorescence, and its brightness and chroma are higher, showing pinkish red colour.