Gemmological Characteristic of Colour Coated Cubic Zirconia

In this paper, the gemmological characteristics of colour coated cubic zirconia samples were studied by microscopic observation, Fourier transform infrared spectrometer(FTIR), scanning electron microscope(SEM) and UV-Vis spectrometer. The results indicated that the colour coated cubic zirconia showed a strong glassy to sub-adamantine luster, and the relative density was 5.6-5.9. By microscope observation, the etched brand mark and the fell off surface film could be observed. Colourless samples and colour coated samples showed characteristic absorption of infrared spectrum of cubic zirconia in the fingerprint region (800-400 cm^-1) without significant difference. The composition analysis showed that the elements of colourless cubic zirconia sample are Zr, Y, Hf, Al, O, and the besides these elements above, the colour coated cubic zirconia samples contain Si, Na, Cr, Fe, Co, Zn, Br, Sn. Coated samples with different colour contain their own unique elements: purple coated cubic zirconia contains Sn; blue coated cubic zirconia contains Br; green coated cubic zirconia contains Zn; yellow coated cubic zirconia contains Na, Fe, Zn. UV-Vis spectra showed that the purple coated cubic zirconia had 540 nm absorption peak, the blue coated cubic zirconia had 546, 585 nm and 628 nm absorption peaks, the green coated cubic zirconia had 606 nm and 660 nm absorption peaks, and the yellow coated cubic zirconia had 417 nm and 500 nm weak absorption peaks. The surface characteristics, absorption spectra and chemical compositions of the samples may provide references for the identification of colour coated cubic zirconia.