"'Dear Sir—In my letter of recent date I offered to you the duplicate of the Aztec Opal which you recently purchased from Mr. Gray. You paid Gray twenty thousand dollars, and I expressed my willingness to sell you mine for five thousand dollars in advance of this sum. In your letter just received, you agree to pay this amount, naming two conditions. First, you ask why I consider my opal worth more than the other, if it is an exact duplicate. Secondly, you wish me to explain what I meant by saying on the yacht that "women are poor conspirators."
"'In reply to your first question, my answer is, that however wealthy I may be I usually do business strictly on business principles. These opals separately are worth in the open market twenty thousand dollars each, which sum you paid to Gray. But considering the history of the gems, and the fact that they are absolute duplicates the one of the other, it is not too much to declare that as soon as one person owns both gems, the value is enhanced twofold. That is to say, that the pair of opals together would be worth seventy or eighty thousand dollars. This being true, I consider it fair to argue that whilst I should not expect more than twenty thousand dollars from any other person in the world, twenty-five thousand is a low sum for me to ask of the man who has the duplicate of this magnificent harlequin opal.
"'In regard to my remark about the "conspirators," the conspiracy in which I had induced Mrs. Gray to take part was entirely honorable, I assure you. I knew of Gray's financial embarrassments and wished to aid him, without, however, permitting him to suspect my hand in the affair. He is so sensitive, you know. I therefore suggested to Mrs. Gray that she entrust her jewel to me, and promised to dispose of the two jewels together, thus realizing the enhanced value. I pointed out that in this manner she would be able to give her husband much more than he could possibly secure by the sale of the one stone.
"'Trusting that I have fully complied with your conditions, I will call upon you at noon to-day, and will bring the opal with me. We can then complete the transaction, unless you change your mind in the interval. Cordially yours, etc.'
"So you see," said Mr. Mitchel, "he offers to sell me his opal, rather than to purchase mine."
"It is strange," said Mr. Barnes, musingly. "Why should he relinquish his hope of getting possession of that mine? I do not believe it. There is some devilish trickery at work. But let me tell you the rest of my story."
"Oh, is there more?"
"Why, certainly. I have not yet explained my reason for thinking you might be in danger."
"Ah, to be sure. My danger. I had forgotten all about it. Pardon my stupidity."
"In further conversation with this Sanchez I put this proposition to him. 'Suppose,' said I, 'that your friend Domingo had one of these opals, and knew the man who had the other. What would he do?' His answer was short, but to the point. 'He get it, even if he kill.'"