"Hush," said Kino. "Do not speak any more. In the morning we will sell the pearl, and then the evil will be gone, and only the good remain. Now hush, my wife." (3.78)
It’s unclear whether Kino is patronizing his wife by calling the pearl "evil" or whether he truly acknowledges its nature.
"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.