A Nondestructive Sr/Ca‐Based Indicator for Distinguishing Seawater and Freshwater Pearls

ABSTRACT A rapid and nondestructive method for distinguishing seawater and freshwater pearls is presented based on the geochemical Sr/Ca signature archived during biomineralization. X‐ray fluorescence (XRF) measurements of 42 seawater and 36 freshwater spots reveal a fourfold difference in the Sr/Ca regression slopes (0.0069 vs. 0.0017), with non‐overlapping 95% confidence intervals, confirming statistically distinct origins. Raman spectroscopy shows reduced carbonate‐band intensities in seawater pearls due to Sr‐induced lattice distortion, although the intensity ratio lacks quantitative discriminative power. These results demonstrate that the XRF‐derived Sr/Ca ratio serves as a reliable primary indicator, with Raman providing complementary microstructural insight for pearl identification.