Papers by Author: Ying Guo

Abstract: To evaluate the quality and simulate the discrimination of rubelite red, 310 rubelite red samples are measured by color i5 colorimeter, based on CIE 1976 L*a*b* uniform color space. Conclusions show that the hue angle of rubelite red can be classified into four series, such as red, pink, purple and violet, and the chroma can be divided into light, medium and intense, vivid with increasing quality, then its lightness can be graded into five levels as dark, slightly dark, medium, slightly bright and bright under standard light source D65. Take the three parameters and the cluster analysis of color coordinates, the rubelite red can be grade into five levels, and it is supposed to predict unknown samples furthermore.

Abstract: The aim of this paper is to research human visual differentiation of lavender jadeite-jade classification through color difference.The result of E*2000 matches human eyes best. Based on that, using Color i5 for measuring Color parameters of jade samples and analyzing the differences of the color appearance among L*2000, C*2000 and H*2000.Taking consideration that variation range of purple is wide in color science, although L*2000 contributes most to E*2000(r=0.854), it is extremely not rigorous if we ignore the influence of H*2000 or C*2000. L*2000 less than H*2000 and C*2000 for all the lavender of jadeite parameters affecting the appearance.

Abstract: Through to 110 pieces purity transparent and color uniform, 3 x 5 x 7mm blue synthetic spinel made with the flame fusion method on chemical compositions and color parameter measurement the Co²⁺ content and color changes, clear the influence on Co²⁺ relationship of blue synthetic spinels’ color appearance. Through LA-ICP-MS to analysis the cause of colorant content, proof that with Co²⁺, the increase of the content of synthetic spinel will shift blue to purple tone, and C^* shows a parabola form with the drop of L^*, 700 ppm ~ 900 ppm place in peak. DL^* Î (3.55 ~ 76.94) with Co²⁺ Î (4.59 ppm ~ 1849 ppm) change the largest amount, DC^* Î (-9.99 ~ 29.32) next, DH^* Î (-20.34 ~ 4.67) compared with before two changes smallest. Co²⁺ content in 100ppm below, blue color of synthetic spinel with Co²⁺ content increased changes greatly; 500 ~ 1500 ppm, visually achieve optimal color (C^* higher); above 1500ppm, because of the Co²⁺ overmuch make the color burn cause the overall decline of transparency, the change of L^* tends to be gentle, C^* decrease obviously. Use Color i5 in standard color measurement instrument lighting source D65, measured the lightness L*, specimen Color a^* and b^*, chroma C^* and tonal angle h_o, based on the uniform color space CIE 1976 L^*a^*b^*, in lightness minimum L 9-10 specimen (processing data for standard to 9th), with the help of DE2000 benchmark for calculating formulas, the Color, the color difference train E^* by partial correlation analysis card clearly degrees of off color changes L^* has certain influence on rD_L*×D_E* = 0.996, while rD_C*×D_E*= -0.427, rD_H*×D_E* = -0.339. Conclusion, the bule color of synthetic spinel because of its Co²⁺ content changes main influencing L^* to contribute to its color appearance.

Abstract: 10 pieces of yellowish green peridot from Jilin province with fine and pure texture were selected to analyze the relationship between frequency drift in middle-infrared band and color appearance, through the replacement of Fe²⁺. The actual crystal chemical formula of the samples calculated by Oxygen atom method is: (Mg_1.84,Fe_0.19)_2.04[(Si_0.982,Al_0.001)_0.983O₄], so prove that it is chrysolite [1] and the replacement of Fe²⁺ and Mg²⁺ in the position M, which led to the yellowish green appearance. With the help of Fourier infrared spectrometer TENSOR27 and One Way ANOVA analysis study the infrared spectra of 10 samples and analyze the impact Fe2+ had on frequency drift, getting the Correlation coefficient r between Fe²⁺ and the wave-number near 1040cm^-1, 622cm^-1, 522cm^-1, and the value of r are -0.896,-0.884,-0.903, therefore, with Fe²⁺ increasing ,three reflection peaks drift to the lower frequency. Compare the reflectivity in the visible area (360nm ~ 750nm) tested by colorimeter Color i5 with the mafic peridot end of forsterite solid solution, finding that with the reflectance peaks drift to low frequency, reflection of blue and purple light decrease, blue and purple tone in peridot decreasing; reflection of the red and orange light increases, red and orange tone increasing. It is concluded that in the transformation of mafic Peridot end to chrysolite peridot end, reflection peaks in infrared band drift to lower frequency, causing the increase of red and orange tone, decrease of blue and purple tone in Peridot.

Abstract: According to different light sources and cathodoluminescence (CL) intensity, the performance of color parameters (lightness L^*, chromaticity a^* and b^*, chroma C^*, hue angle h_o) and chromophore contents (Cr³⁺, åFe) are studied to analyze the impact of all these elements on ruby red color. Ruby red under the standard light source D65 (a^*=5.65 ~ 26.97, b^*= -5.43~3.98) is similar with the color under natural sun-light. Purplish red h_o Î (354.14°, 0.7°) with medium-low lightness (L^* = 32 ~ 40) under D65 displays the best visual appearance, showing a relatively high value. Comparing with D65, standard light source A reveals ruby a deep red hue (a^* = 10.61 ~ 37.39, b^* = -6.59 ~ 7.50). Because of the strongest spectrum power distribution in the orange range and fluorescence of light source U30, the hue of orangish tone is mixed in ruby red (a^* = 6.92 ~ 31.23, b^* = 0.31 ~ 9.34). It is illustrated that åFe can inhibit the intensity of CL which is compared in different voltages. Low lightness purplish red is easy to be influenced by CL and always shows strong luminescence correspondingly. It is concluded that ruby purplish red has strong luminescence of CL which is usually supported by a few of åFe and medium-low lightness under D65, which has an excellent visual perception.

Abstract: Under A, CWF, D55, D65, D75 five different illuminants, color differences of 53 natural oval Jadeite-jade with fine texture are analyzed, which color is yellow-green to dark green. All 5 tested lighting sources were compared based on the uniform color space CIE 1976L*a*b*. Jadeite-jade’s lightness L* is increasing when color temperatures of five different standard illuminants increase, and it can reach the very top of 45.72 under D75, so it appears brighter and lighter than any other illuminants and it influences the appraisal of the samples’ color. The spectrum power distribution of D75, D65 and D55 reveal the strong radiant energy in the range from 500 to 570nm, so consequently the color coordinates a*, b* and chroma C* is higher than the other two illuminants. But samples’ lightness and chroma under D55 are weaker compared to D65 and the color under D55 is dark. Meanwhile, D65 stands for the average daylight and color under D65 close to the true color of samples. Because of weakest radiant energy in the range from 500 to 540nm (green area) and strongest radiant energy in the range from 540 to 570nm (orange area) in CWF’s spectrum power distribution, the absolute value of a*=14.01 is lowest and b*=12.93 is highest under CWF, so samples’ color under CWF is green with a yellow tint. The maximum hue angle h0 is 150.42 under A, and the absolute value of a* is higher than that under CWF, so it shows stronger green tone than CWF. It is concluded that D65 is preferred to be ideal illuminants for the evaluation of jadeite-jade color green especially compared with other 4 illuminants.

Abstract: Twenty-eight yellow-green color of uniform, high clarity and similar thickness of 5 mm × 7 mm oval faceted peridots from Jiaohe Jilin province were examined by LA-ICP-MS and Color i5 to test their chemical compositions and L^*, C^* and ho. The correlations between Fe²⁺ and color parameters were analyzed, in order to establish the influence on the color appearance of Fe²⁺. The chemical formula of the twenty-eight peridots is (Mg_1.84,Fe_0.19)_2.04[(Si_0.982,Al_0.001)_0.983O₄], which was calculated by oxygen atom. It reveals that 0.19 mol Fe²⁺ is concluded in one mol peridot, and Fe²⁺ is the colorant of peridot. Based on the CIE 1976 L^*a^*b^* uniform color space, relationships between chromaticity coordinates a^*, b^* and chromaticity C^* were analyzed by Two-way ANOVA, of which the results showing that the influence of b^* on C^* (r_b*×C*=0.996) is much more prominent than a^* on C^* (r_a*×C* = -0.383). By partial correlation analysis of the results calculated through CIE LAB color-difference formula, it can be discovered that lightness difference DL^* has a better correlation with chromatic aberration DE^* than DC^* and DH^*, whereas the significance level ρDC*×DE* > 0.05, rDH*×DE* > 0.05, it reveals that DE^* is more sensitive to DL^*. At the same time, L^* changes the most with the contributions of Fe²⁺ compared with other parameters of peridot. It is concluded that, with the help of L^*, Fe²⁺ has a further influence on the color appearance of peridot.

Abstract: Its play-of-color effect of Australian opal makes it unique and much more precious than any other gemstones in the world. More than 50 Australian opals were chosen to conduct the experiments, including boulder and black opals with blue-green to blue-purple color. Spectropotometer Color i5 was used to analyze the color of opal samples with CIE L^*a^*b^* uniform color space. Dominant wavelength was put into comparison with hue angle. SEM and AFM were the main means to analyze the internal structure of opal samples, and the diameter and size of cavities of SiO₂ were measured and discussed. It is revealed that the hue angle of blue-purple opal is 302.15° with 449nm as its dominant wavelength, and so the size of SiO₂ cavities in the sample is about 155.32nm; the hue angle of blue opals is between (256°, 286°) with the dominant wavelength between (471nm, 485nm), and so their size of SiO₂ cavities is between (154.35nm, 182.54nm); the hue angle of blue-green opal is between (183°, 213°) with the dominant wavelength between (489nm, 500nm) and so their size of SiO₂ cavities is between (172.95nm, 193.66nm). Besides, the diameter and size of SiO₂ cavities were analyzed against the dominant wavelength, hue angle, lightness, and saturation to reveal their correlation. It is indicated that the diameter and size of SiO₂ cavities are in positive correlation with the dominant wavelength, but negative correlation with the hue angle. As the diameter and size of SiO₂ cavities grow, the dominant wavelength increases but the hue angle decreases. Also they are in positive correlation with lightness but their correlation with saturation was not discovered.

Abstract: In this paper,DTA-TG and TEM are used to investigate dolomite containing phosphorus. The investigations suggest that the thermal decomposition of dolomite containing a little bit of phosphorus powder has only one reaction while that of dolomite has two reactions, and the final temperature of the reaction reduces by about 18°C. The oxidation reaction of the phosphorus in dolomite begins at about 500°C, which is 140°C higher than that of the oxidation reaction of phosphorus in standard atmosphere condition. Round-bubble-shape structure gradually appears on the surface of the dolomite sample when observed using TEM. Furthermore, the number and size of this structure increased with the rising of the temperature. Finally, the round-bubble-shape structure breaks to small hollows, showing as teared-shape, and forms a series of protruding and intensive larger hollows and spherical shape. Therefore, the temperature of thermal decomposition of thermal decomposition of dolomite is decreased and the components of thermal decomposition products of dolomite containing phosphorus are almost the same as that of dolomite.

Abstract: The correlations between of lightness, chroma, Cr3+ and color index were studied to analyze the impact of all these three elements on ruby red color; and with the color difference research, the lightness difference is testified to be the key affecting color appearance. Based on the uniform color space CIE 1976L*a*b*, the ruby displays the best red color when the content of Cr3+ is within (1555, 5183ppm), L* (32.64, 44.25) and ho  (354.14, 0.7). With the help of partial correlation analysis of color difference, it is illustrated that the correlation between L* and E* (r=0.999) is relatively higher than that between L* and E* (r=0.948); and with high significance level ( = 0.129) of H* and E*, it shows that H* has little impact on E*. It is concluded that the color change of ruby from red to purple are mostly affected by lightness change; lightness difference should be considered as the most important factor when evaluating the red color of ruby, and then followed by the chroma and hue jointly.