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Free keywords:
biomineralization, calcium carbonate microstructures, pearl cultivation, pearl layer development
Abstract:
Cultivated pearls frequently exhibit morphological irregularities making obvious that mineral deposition was irregularly distributed onto nucleus surface. Taking advantage of experimental cultivations with short durations (from 10 days to few months), these irregular deposits predating occurrence of the nacre were investigated in Polynesian pearls by biochemical characterizations and a series of physical methods. Diversity in the resulting data suggests that various in-depth alterations of the biomineralization mechanism may have occurred during the grafting process, leading to diversity in the biochemical pathways to nacreous deposition. This allows a precise discussion of current views about pearl formation. The ?reversed shell theory? is formally disproved through point to point comparison with development of the shell growing edge. Similarity of pearl formation with ?regeneration? or ?shell repair? is also discussed, emphasizing the differences between these concepts.
