In this study, we comparatively investigated the gemological and fine-microstructural characteristics of yellow seawater pearls cultured in Pinctada fucata martensii using X-ray computed microtomography (μ-CT) analysis, ultraviolet-visible (UV−Vis) reflectance spectroscopy, field emission scanning electron microscope (FE-SEM), Raman and photoluminescence (PL) spectroscopy, and Laser ablation−inductively coupled plasma−mass spectrometry (LA−ICP−MS). Detection of the nacre thickness indicated that the average nacre thickness varied from 0.17 to 1.35 mm, and further theoretical calculations showed that the nacre accounted for about 15–68% of the whole pearl by volume. For yellow or light-yellow pearls, the spectroscopy results showed characteristic patterns such as certain distinct absorption features around 360, 400, 430, and 450 nm in the UV−Vis reflection spectra and the organic pigment-related peaks at approximately 1130 and 1530 cm^–1 in the Raman spectra. Furthermore, dominant aragonite peak intensities were observed in the PL spectra of these samples, with the ratio between the overall fluorescence intensity (F) and the height of the main aragonite peak (A) consistently below 5. SEM observations showed that multiple amorphous structures, mainly composed of aragonite, coexisted in the nacre in these portions of the pearls, one of which was closely adjacent to the nucleus of the pearl. In addition, LA-ICP-MS analysis clearly revealed the nacre of the outer saltwater layers and the inner freshwater nucleus. Interestingly, we directly observed that the quantities of Na and Mg in the nacre were higher than that those in the freshwater nucleus. These findings substantially enhanced our knowledge of gemological, mineralogical, and fine-microstructural characteristics of as-grown yellow seawater pearls. Most importantly, this study revealed some key characteristics that could be used to identify imitation and color-treated yellow pearls and further guide the pearl production.

在本研究中，我们利用 X 射线计算机显微断层扫描 (μ-CT) 分析、紫外可见 (UV−Vis) 反射光谱、场发射扫描等方法，比较研究了马氏珠母贝养殖的黄色海水珍珠的宝石学和精细微观结构特征。电子显微镜 (FE-SEM)、拉曼光谱和光致发光 (PL) 光谱以及激光烧蚀电感耦合等离子体质谱 (LA−ICP−MS)。珍珠层厚度检测表明，珍珠层平均厚度为0.17～1.35毫米，进一步理论计算表明，珍珠层体积约占整颗珍珠的15%～68%。对于黄色或浅黄色珍珠，光谱结果显示出特征模式，例如紫外可见反射光谱中 360、400、430 和 450 nm 附近的某些明显吸收特征以及约 1130 和 1530 cm-1 处的有机颜料相关峰拉曼光谱中的^{–1 。}此外，在这些样品的 PL 光谱中观察到主要文石峰强度，总荧光强度 (F) 与主文石峰高度 (A) 之间的比率始终低于 5。SEM 观察表明，多个非晶结构，主要由文石组成，共存于珍珠这些部分的珍珠层中，其中之一紧邻珍珠核。此外，LA-ICP-MS 分析清楚地揭示了外部咸水层和内部淡水核的珍珠质。有趣的是，我们直接观察到珍珠层中Na​​和Mg的含量高于淡水核中的含量。这些发现极大地增强了我们对黄色海水珍珠的宝石学、矿物学和精细微观结构特征的了解。最重要的是，这项研究揭示了一些关键特征，可用于识别仿制和颜色处理的黄色珍珠，并进一步指导珍珠生产。