“It is jade undoubtedly, although I have never seen jade exactly like it—I, who have studied every known species of precious and semi-precious stone.”
“Then why do you say it is jade?”
“Because I know that. I have analyzed it. It is chloromelanite, consisting of a silicate of aluminium and sodium, with peroxide of iron, peroxide of manganese, and potash. It has been broken from a greater piece—perhaps from an enormous piece. The example I have previously seen that most resembled this was found in the Kara-Kash Valley of Turkestan; but that was not nearly so transparent. That piece you hold in your hand is more fusible than nephrite, which is the commoner form of jade; and it has a specific gravity of 3.3.”
“What makes you believe it was broken from a larger piece?”
“I know by the arc of the curve of the one side, and by the shape of the fracture on the other, that it has been broken by external violence from a piece considerably larger than itself. I have worked out a law of vibration and fracture that is as interesting in its way as Einstein’s law of relativity. Do you understand mathematics?”
“No. I’ll take your word for it. What else do you know positively?”
“Positively is the only way to know,” the jeweler answered, screwing up his face until he looked almost like a Chinaman. “There was human blood on it—a smear on the fractured side, that looked as if a careless attempt had been made to wipe it off before the blood was quite dry. Also the print of a woman’s thumb and forefinger, plainly visible under the microscope, with several other finger-prints that certainly were Tin Lal’s. The stone had come in contact with some oily substance, probably butter, but there was too little of it to determine. Furthermore, I know, Ommonee, that you are afraid of the stone because to touch it makes you nervous, and to peer into it makes you see things you can not explain.”
Ommony laughed. The stone did make him nervous.
“Did you see things?” he asked.
“That is how I know it makes you see them, Ommonee! Compared to me you are a child in such respects. If I, who know more than you, nonetheless see things when I peer into that stone, it is logical to my mind that you also see things, although possibly not the same things. Knowing the inherent superstition of the human mind, I therefore know you are afraid—just as people were afraid when Galileo told them that the earth moves.”