Pearl Oyster Research Group, School of Marine & Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia.
Mar Drugs. 2010 Sep 20;8(9):2517-25. doi: 10.3390/md8092517.
Two groups of commercial quality ("acceptable") pearls produced using two donors, and a group of "acceptable" pearls from other donors were analyzed using reflectance UV-Vis spectrophotometry. Three pearls with different colors produced by the same donor showed different absorption spectra. Cream and gold colored pearls showed a wide absorption from 320 to about 460 nm, while there was just slight reflectance around 400 nm by the white pearl with a pink overtone. Cream and gold pearls reached a reflectance peak at 560 to 590 nm, while the white pearl with pink overtone showed slightly wider absorption in this region. Both cream and gold pearls showed an absorption peak after the reflectance peak, at about 700 nm for the cream pearl and 750 nm for the gold pearl. Two other pearls produced by the same donor (white with cream overtone and cream with various overtones) showed similar spectra, which differed in their intensity. One of these pearls had very high lustre and its spectrum showed a much higher percentage reflectance than the second pearl with inferior lustre. This result may indicate that reflectance is a useful quantitative indicator of pearl lustre. The spectra of two white pearls resulting from different donors with the same color nacre (silver) showed a reflectance at 260 nm, followed by absorption at 280 nm and another reflectance peak at 340 nm. After this peak the spectra for these pearls remained flat until a slight absorption peak around 700 nm. Throughout the visible region, all white pearls used in this study showed similar reflectance spectra although there were differences in reflectance intensity. Unlike the spectral results from white pearls, the results from yellow and gold pearls varied according to color saturation of the pearl. The results of this study show that similarities between absorption and reflectance spectra of cultured pearls resulting from the same saibo donor are negligible and could not be detected with UV-Vis spectrophotometry. Nevertheless, this technique could have a role to play in developing less subjective methods of assessing pearl quality and in further studies of the relationships between pearl quality and that of the donor and recipient oysters.
两组由两位供体生产的商业品质（“可接受”）珍珠和一组来自其他供体的“可接受”珍珠使用反射式紫外-可见分光光度法进行了分析。同一供体生产的三种不同颜色的珍珠显示出不同的吸收光谱。奶油色和金色珍珠在 320 至约 460nm 范围内显示出广泛的吸收，而带有粉红色调的白色珍珠在 400nm 左右只有轻微的反射。奶油色和金色珍珠在 560 至 590nm 处达到反射峰，而带有粉红色调的白色珍珠在该区域显示出稍宽的吸收。奶油色和金色珍珠在反射峰后都显示出一个吸收峰，奶油色珍珠在 700nm 左右，金色珍珠在 750nm 左右。同一供体生产的另外两颗珍珠（带有奶油色调的白色珍珠和带有各种色调的奶油色珍珠）显示出相似的光谱，但在强度上有所不同。其中一颗珍珠具有非常高的光泽度，其光谱显示出比第二颗光泽度较低的珍珠反射率高得多的百分比。这一结果可能表明反射率是珍珠光泽度的一个有用的定量指标。来自不同供体的两颗具有相同颜色珍珠母（银色）的白色珍珠的光谱在 260nm 处显示出反射率，随后在 280nm 处吸收，在 340nm 处再次出现反射率峰值。在这个峰值之后，这些珍珠的光谱一直保持平坦，直到在 700nm 左右出现一个轻微的吸收峰。在整个可见光谱范围内，本研究中使用的所有白色珍珠都显示出相似的反射率光谱，尽管反射率强度有所不同。与白色珍珠的光谱结果不同，黄色和金色珍珠的结果根据珍珠的颜色饱和度而有所不同。本研究的结果表明，来自同一供体的养殖珍珠的吸收和反射光谱之间的相似性可以忽略不计，并且无法用紫外-可见分光光度法检测到。尽管如此，这种技术在开发评估珍珠质量的非主观方法和进一步研究珍珠质量与供体和受体牡蛎之间的关系方面可能具有一定的作用。
