365nm紫外线所激发钻石荧光颜色的测量分析

Measurement and Analysis of Diamond Fluorescent Emission Colour under 365 nm Ultraviolet Excitation

目前,对于长波紫外线下钻石荧光的颜色描述大多数采用肉眼观察,缺乏颜色定量分析。采用USB4000光纤光谱仪及365nm的发光二极管作为紫外线光源测试了45颗天然无色—近无色钻石样品的荧光光谱数据,并结合色度学理论,获得其荧光颜色的色品坐标,将钻石的荧光颜色大致分为3类。在同样强度的365nm紫外线激发下,结果显示:(1)钻石样品的蓝色荧光在饱和度和强度上均比其它颜色荧光的高,绿色荧光次之,其余荧光颜色微弱;(2)肉眼观察钻石样品的荧光呈现粉色和橙黄色时,其所测试数据在CIE色度图中的位置均位于蓝色区域,而肉眼观察为绿色荧光在CIE色度图中的位置在绿色区域;(3)蓝色荧光的亮度和饱和度均比较高,且荧光光谱的波峰位置基本相似,主波长分布于471~483nm中并在CIE色度图中各点的位置相对紧凑,而绿色荧光的波峰不定,主波长分布于473~510nm中并在CIE色度图中的位置比较分散。

Most gemmological descriptions on the colour of diamond fluorescence is based on observation by naked eye, and lacks of precise quantitative fluorescence colour determina-tion. In this paper, the authors studied the ultraviolet fluorescence colour of natural near- colourless diamond samples by using USB4000 and light-emitting diode （LED） with 365 nm emission. The fluorescence spectra of 45 natural near-colourless diamonds were measured and analyzed by using theory of colorimetry in order to get the chromaticity coordinates and other related colorimetric parameters. From the calculation, the authors divided the fluores-cent colour of diamonds into three categories. Under the same intensity of 365 nm ultraviolet excitation, blue fluorescence in both saturation and intensity are highest among other fluo-rescence colours. Under microscopic observation, fluorescence colour of diamonds showed blue, pink, yellow, but all calculated main hue still resided in a rather concentrated blue area （dominant wavelength： 476 - 478 nm） in the CIE chromaticity diagram. However, dominant wavelength of the green fluorescence falls between 473-510 nm with a wide span.