I've been reading Casanova's memoirs, and I came across a section which puzzled me:

​

"I am afraid marriage is out of the question for me, because I want, for instance, my wife to have black eyes, and in our days almost every woman colours them by art; but I cannot be deceived, for I am a good judge.”

“Are mine black?”

“You are laughing?”

“I laugh because your eyes certainly appear to be black, but they are not so in reality. Never mind, you are very charming in spite of that.”

“Now, that is amusing. You pretend to be a good judge, yet you say that my eyes are dyed black. My eyes, sir, whether beautiful or ugly, are now the same as God made them. Is it not so, uncle?”

“I never had any doubt of it, my dear niece.”

“And you do not believe me, sir?”

“No, they are too beautiful for me to believe them natural.”

​

Full text available here.

​

The lady in question then becomes quite angry at the fact that Casanova does not believe her eyes to be real, and the conversation dies out for a bit. Casanova then suggests a "means of ascertaining the truth":

​

There can be no true black eyes now for you in the world, but, as you like them, I am very glad of it.”

“You are mistaken, lovely Christine, for I have the means of ascertaining the truth.”

“What means?”

“Only to wash the eyes with a little lukewarm rose-water; or if the lady cries, the artificial colour is certain to be washed off.”

​

I've searched online but have been unable to find any reference to this custom, so I was hoping a scholar here might be able to enlighten me! Thank you for your attention

​

Edit: For additional context, this event would have occurred in the 1740s in Italy