Have you heard this? Set the scene. Queen Cleopatra is dining with the Roman Statesman, Marc Anthony. She is holding a large pearl.

Oil painting on canvas, Cleopatra dissolving the Pearl in Wine by Andrea Casali (Rome 1705 - Rome 1784). Cleopatra seated at a table dropping a pearl into a bowl of wine watched by Mark Anthony with soldiers and figures in the background preparing the banquet. According to Pliny the Elder in his Natural History, Cleopatra

The story of Cleopatra's pearl is told by Pliny the Elder in his Natural History (9. 119-21): 'There have been two pearls that were the largest in the whole of history; both were owned by Cleopatra, the last of the Queens of Egypt—they had come down to her through the hands of the Kings of the East....In accordance with previous instructions the servants placed in front of her only a single vessel containing vinegar, the strong rough quality of which can melt pearls. She was at the moment wearing in her ears that remarkable and truly unique work of nature. Antony was full of curiosity to see what in the world she was going to do. She took one earring off and dropped the pearl in the vinegar, and when it was melted swallowed it.'

So, it must be true.