E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Cleopatra and her Pearl.
It is said that Cleopatra made a banquet for Antony, the costliness of which excited his astonishment; and, when Antony expressed his surprise, Cleopatra took a pearl ear-drop, which she dissolved in a strong acid, and drank to the health of the Roman triumvir, saying, My draught to Antony shall far exceed it. There are two difficulties in this anecdotethe first is, that vinegar would not dissolve a pearl; and the next is, that any stronger acid would be wholly unfit to drink. Probably the solution is this: the pearl was sold to some merchant, whose name was synonymous with a strong acid, and the money given to Antony as a present by the fond queen. The pearl melted, and Cleopatra drank to the health of Antony as she handed him the money. (See Gresham in Readers Handbook.)