Since pearls are made mostly of
calcium carbonate, the acid found in vinegar, known as
acetic acid, will definitely dissolve one over a period of time. The same dissolution would occur if an egg were placed in a glass of vinegar and left to sit - the egg shell would disintegrate. Of course, the speed as which the pearl dissolves will depend on the concentration of the acid and the pearl's overall size. The reaction produces calcium acetate, water and carbon dioxide, summarized below:
\(\mathrm{CaCO_3+2CH_3COOH\ →\ Ca(CH_3COO)_2+H_2O+CO_2}\)
More Pearly Facts: Mollusks actually create pearls as a form of protection from foreign particles, sand and parasites. Natural pearls, though, are very rare in modern times due to a decline in mollusks ...