Spectroscopic OCT: towards an effective tool for distinguishing authentic and artificial Chinese freshwater pearls

Distinguishing authentic and artificial Chinese freshwater pearls involves various tools and techniques, based primarily on visual inspection and spectroscopy. These methods are highly variable and thus not statistically reliable. This study investigates the capacity of spectroscopic optical coherence tomography (S-OCT) to classify authentic and artificial pearls in the NIR spectral range. The major advantage of S-OCT is that it allows spectroscopic measurements from within pearls, unlike traditional methods such as diffuse reflectance spectroscopy that primarily probe the surface. S-OCT spectral data was analyzed using principal component analysis (PCA) and partial least-squares discriminant analysis (PLSDA) to classify pearls. The implemented models successfully predicted pearl type and met performance metrics. The results show that S-OCT models could be used for more objective discrimination of authentic versus artificial pearls.