Cherished for their elegant beauty, pearls are actually very soft and require special care. Vinegar, in particular, must be avoided, as it's capable of dissolving pearls.
Pearls consist of a substance called nacre, which is made from marble, limestone and calcium carbonate.
When pearls are dropped in white vinegar, the acetic acid in the vinegar reacts with the calcium carbonate in the pearl, releasing carbon dioxide and dissolving the pearl.
The exact time needed to dissolve the pearl depends on several factors, including the acidity level of the vinegar, the temperature and the pearl surface area exposed to the reaction.
Vinegar actually provides the best way to authenticate a pearl. Place a small drop of vinegar on the pearl, and if it fizzes, the pearl is real. Fake pearls won't react to vinegar.
According to Pliny, a first-century historian, Cleopatra once dissolved an extravagant pearl in a goblet of wine vinegar and drank it in order to win a wager with Mark Antony.