The Contribution of Cu2+, Fe2+, Fe3+ to Bluish Green Color of HuBei Turquoise

Fe2+, Cu2+, Fe3+ and Fe3+ of 146 piece turquoise from ZhuShan, HuBei province are researched of their contribution to the color of bluish green. Without consideration of its mineral water on the effects of color chroma, the content of these three cations are confirmed by chemical composition analysis, and then their specific contribution to lightness, chroma and hue are quantified within the uniform color space CIE L* a* b*. Consequently, it is considered that Cu2+ determines turquoise's vivid blue, and Fe2+ makes color changed to green and improves the chroma slightly, as a result it enhances the visual appearance a little too; while Fe3+ leads to red and yellow tone and makes chroma descended simultaneously, with its increment, the color appears low saturated brown, and then the color quality reduced.