Mr. Barnes obeyed, and for an instant Mr. Livingstone seemed weighing his chances, but evidently deciding that the odds were in all ways against him, he rushed from the apartment and out of the house.
"Well, Mr. Mitchel," said Mr. Barnes, "now that the danger has passed, an explanation seems to be in order. You seem to have four opals."
"Yes; but that is merely seeming. You will readily understand why I wished your eyes, for without them I could not have taken my own off of the opals even for an instant."
"Then you purposely turned your back when you went to get the silver band?"
"Assuredly. Why could I not have taken out the band in the first instance, and why did I lock the safe, making it necessary for me to take time with the combination? Simply to give my man the opportunity to do his trick. You see, I knew before he came here exactly what he would do."
"How did you know?"
"You will recall that in his letter he offers to sell me the duplicate opal. That made me smile when I read it, for I already had been notified that he had had duplicates of his opal made."
"You had been notified?"
"Yes. This whole affair flatters my vanity, for I anticipated the event in its minutest detail, and all by analytical deduction. You quite correctly argued that Livingstone would not abandon his quest of the opal. I also reached that point, and then I asked myself, 'How will he get it, knowing that I would not sell?' I could find but one way. He would offer to sell his, and during the transaction try to steal mine. As he would need both opals in his Mexican mining venture, his only chance of carrying both away with him would be to have two others to leave in their stead. Thus I argued that he would endeavor to have two duplicates of his opal made. Ordinarily, opals are not sufficiently expensive to make it pay to produce spurious specimens. Consequently, it has been little done; indeed, I doubt that the members of the trade in this city have any idea that doublet opals have been made and sold in this city. But I know it, and I know the man who made the doublets. These were common opals, faced with thin layers of a fine quality of 'harlequin' which often comes in such thin layers that it is practically useless for cutting into stones, though it has been utilized for cameos and intaglios. This lapidary does his work admirably, and his cement is practically invisible. I went to this man and warned him that he might be called upon to duplicate a large and valuable opal, and I arranged that he should fill the order, but that he should notify me of the fact."
"Ah, now I understand. The genuine opals lay on the desk, and when you turned to the safe Livingstone merely exchanged them for the spurious doublets. But tell me why did he risk bringing the real opal here at all? Why not offer you one of the doublets, and then merely have one exchange to make?"