A Case Study: GRS“Pigeon's blood”Ruby Colour Analysis and Implications

In order to test the criteria provide by the GRS certificate for“pigeon’s blood”ruby，the authors use microspectrophotometer to measure the transmittance value of several GRS“pigeon’s blood”ruby samples.On one hand，colorimetric measurements of the samples are converted to CIE chromaticity coordinates for the quantitative range of colour of GRS“pigeon’s blood”ruby.On the other hand，the authors exclude the effects of pleochroism and fluorescence on the colour measurement，and explain the reasons for some metamerism ruby which can’t be called“pigeon’s blood”ruby with the help of gemmology theories.According to the research and analysis，GRS defines those vivid red rubies with features of Burma ruby as“pigeon’s blood”rubies.