Abstract：Mingxi in Fujian Province is one of China's most important sapphire origins, and the gemological research on sapphires from this area is still scarce. In addition, there is currently limited research on the fluorescence characteristic of blue sapphires. This study investigated a batch of sapphires with the “trapiche” phenomenon from Mingxi, Fujian, by conventional gemological instruments, laser denudation plasma mass spectrometer, Raman spectroscopy, and three-dimensional fluorescence spectrometer. The chemical composition and Raman spectroscopy results show that the core, arm, and main body of the “trapiche” gem are composed of corundum and should belong to the “trapiche-like” series.The concentrations of Fe, Ti, and other chromogenic elements in the “trapiche-like” sapphire exhibit no significant variation across different regions, suggesting that the “trapiche-like” phenomenon is not correlated with the distribution of chromogenic elements. The analysis of trace elements and their ratios indicates that the samples exhibit geochemical characteristics consistent with basaltic sapphires, however, the chromium content is mostly higher than >40 ppmw in Mingxi, Fujian basaltic sapphires exceeding that of other basaltic sapphires. Both Raman spectroscopy and fluorescence spectrometer detected several Cr fluorescence peaks of the samples at or near 694 nm. In the three-dimensional fluorescence spectroscopy test, the optimal excitation wavelengths for Cr fluorescence peaks are 410 and 560 nm. The fluorescence intensity of the arm is stronger than that of the core and the main body，which may be caused by the lower concentration of Fe element in the arm. The appearance of Cr fluorescence in the three-dimensional fluorescence spectrum may be related to the higher concentration of Cr element compared with basaltic sapphires originating from other places. Combined with previous studies, it can be differentiated from basaltic sapphires from Laos by observing whether it has the fluorescence peaks of Cr, but this cannot be used to distinguish basaltic and metamorphic sapphires. This study indicates that Mingxi, Fujian has “trapiche-like” sapphires, and the fluorescence spectroscopy results in this study not only enrich the spectroscopy data of basaltic sapphires from Mingxi，Fujian but also offer a fresh perspective for origin identification studies.
