Now the tension which had been growing in Juana boiled up to the surface and her lips were thin. "This thing is evil," she cried harshly. "This pearl is like a sin! It will destroy us," and her voice rose shrilly. "Throw it away, Kino. Let us break it between stones. Let us bury it and forget the place. Let us throw it back into the sea. It has brought evil. Kino, my husband, it will destroy us." And in the firelight her lips and her eyes were alive with her fear. (3.75)
Here it is Juana, not Kino, who has the incisive ability to recognize evil.
"Kino, this pearl is evil. Let us destroy it before it destroys us. Let us crush it between two stones. Let us – let us throw it back in the sea where it belongs. Kino, it is evil, it is evil!"
And as she spoke the light came back in Kino's eyes so that they glowed fiercely and his muscles hardened and his will hardened.
"No," he said. "I will fight this thing. I will win over it. We will have our chance." His fist pounded the sleeping mat. "No one shall take our good fortune from us," he said. His eyes softened then and he raised a gentle hand to Juana's shoulder. "Believe me," he said. "I am a man." And his face grew crafty. (4.84 – 4.88)
The word "crafty" is an interesting choice here, since it has not-so-great connotations that one might even call "evil." The pearl is clearly affecting him.
"I was attacked in the dark," said Kino. "And in the fight I have killed a man."
"Who?" asked Juan Tomás quickly.
"I do not know. It is all darkness – all darkness and shape of darkness."
"It is the pearl," said Juan Tomás. "There is a devil in this pearl. You should have sold it and passed on the devil. Perhaps you can still sell it and buy peace for yourself." (5.28 – 5.31)
Everyone except for Kino recognizes the trouble brought on by the pearl.