"Do you mean that Miss Livingstone was the thief?"
"No. Being hysterical, Miss Livingstone changed her seat without realizing it, but that does not make her a thief. Her excitement when with you was due to her suspicions, which, by the way, were correct. But let us return for a moment to the bare arms. That was the clue from which I worked. It was evident to me that the thief was a man, and it was equally plain that, in the hurry of the few moments of darkness, no man would have rolled up his sleeves, risking the return of the attendants with lamps, and the consequent discovery of himself in such a singular disarrangement of costume."
"How do you account for the bare arms?"
"The lady did not tell the truth, that is all. The arms which encircled her neck were not bare. Neither were they unknown to her. She told you that lie to shield the thief. She also told you that her husband wished to sell the Aztec Opal to me, but that she had refused. Thus she deftly led you to suspect him. Now, if she wished to shield the thief, yet was willing to accuse her husband, it followed that the husband was not the thief."
"Very well reasoned, Mr. Mitchel. I see now where you are tending, but I shall not get ahead of your story."
"So much I had deduced before we went on board the yacht. When I found myself alone with Gray I candidly told him of your suspicions, and your reasons for harboring them. He was very much disturbed, and pleadingly asked me what I thought. As frankly, I told him that I believed that he had tried to take the opal from his wife,—we can scarcely call it stealing since the law does not,—but that I believed he had failed. He then confessed; admitted emptying the lamps, though he denied running the boat on the sand-bar. But he assured me that he had not reached his wife's chair when the lamps were brought in. He was, therefore, much astonished at missing the gem. I promised him to find the jewel upon condition that he would sell it to me. To this he most willingly acceded."
"But how could you be sure that you would recover the opal?"
"Partly by my knowledge of human nature, and partly because of my inherent faith in my own abilities. I sent for Mrs. Gray, and noted her attitude of defense, which, however, only satisfied me the more that I was right in my suspicions. I began by asking her if she knew the origin of the superstition that an opal brings bad luck to its owner. She did not, of course, comprehend my tactics, but she added that she 'had heard the stupid superstition, but took no interest in such nonsense.' I then gravely explained to her that the opal is the engagement stone of the Orient. The lover gives it to his sweetheart, and the belief is, that should she deceive him even in the most trifling manner, the opal will lose its brilliancy and become cloudy. I then suddenly asked her if she had ever noted a change in her opal. 'What do you mean to insinuate?' she cried out angrily. 'I mean,' said I, sternly, 'that if any opal has ever changed color in accordance with the superstition, this one should have done so. I mean that though your husband greatly needs the money which I have offered him, you have refused to allow him to sell it, and yet you permitted another to take it from you last night. By this act you might have seriously injured if not ruined Mr. Gray. Why have you done it?'"
"How did she receive it?" asked Mr. Barnes, admiring the ingenuity of Mr. Mitchel.
"She began to sob, and between her tears she admitted that the opal had been taken by the man whom I suspected, but she earnestly declared that she had harbored no idea of injuring her husband. Indeed, she was so agitated in speaking upon this point, that I believe that Gray never thoroughly explained to her why he wished to sell the gem. She urged me to recover the opal if possible, and purchase it, so that her husband might be relieved from his pecuniary embarrassment. I then sent for the thief, Mrs. Gray having told me his name; but would you not like to hear how I had picked him out before he went aboard? I still have that bit of paper upon which I wrote his name, in confirmation of what I say."