"She was curiously calm."

"I believe you know something about precious stones, Mr. Hartmann?"

"Gems are a hobby of mine," he said with a smile.

"I want your opinion. Do you think paste might deceive an expert?"

"At a casual glance--yes, if it were good paste."

"For instance," I said, "if Lady Leconbridge had been wearing the necklace when you approached her would you have known had it been paste?"

"I should," he answered, with a satisfied smile.

"But yours would have been only a casual glance. A man is more likely to be interested in a woman's beauty than in the jewels she is wearing. Besides, you would not expect Lady Leconbridge to be wearing paste."

"I should have known," he said.

"You say Lady Leconbridge was not agitated by her loss?"

"I said she was curiously calm," he answered. "She was hiding her true feelings, perhaps. At the moment the actress may have predominated.

You know, of course, that Lady Leconbridge was an actress before her marriage?"

"Helen Farrow--yes. Wasn't there some gossip about her at the time of her marriage?"

"There was."

"No truth in it, I suppose?"

He shrugged his shoulders.

"Evidently you think there was."

"So much smoke must have had some fire behind it, I am afraid," said the banker. "You have hinted at the delicacy of this affair, so you must ask me no more questions in that direction."

"Her past could hardly have any bearing on the loss of the diamonds,"

I said.

"I should have thought it might have," said Hartmann, "but then I am not a detective."

Quarles shifted his position a little. From the moment he had sat down he had been absorbed in the pattern of the carpet, apparently.

"You might be right, I think," I said. "One thing is certain, an ordinary thief would have great difficulty in dealing with the stones."

"I suppose so."

"He could only pa.s.s them to some one who could afford to bide his time, receiving small payment for the risk he had run?"

"True."

"And it would be extremely awkward for the person in whose possession the stones were found. That is the detective's point of view."

"Such a person might be able to prove that he was a legitimate possessor."

"I was thinking of the Slade case," I answered. "Messrs. Bartrams, the p.a.w.nbrokers, you know, came very badly out of that. They looked uncommonly like receivers of property which they knew had been stolen."

"Now I am out of my depth," said the banker, rising to bring the interview to an end.

"Just one question," said Quarles, looking up suddenly. "Is the necklace in one of your safes in the bank here?"

"Here! It is hardly a joking matter."

"It is not a joke, but curiosity," said Quarles. "I thought you would keep the jewels at Messrs. Bartrams and not here at the bank. It is rather awkward for you, Mr. Hartmann."

"What do you mean?"

"I am wondering how you will explain your possession of Lady Leconbridge's stolen diamond necklace."

Hartmann stretched out his hand to the bell on his table.

"Ring if you want it to be known that Jacob Hartmann, the well-known and much respected banker, is also Bartrams, who have a very bad name, I can a.s.sure you."

"So you are here to trick me?" said Hartmann, thrusting his hands into his pockets as though to prevent himself touching the bell.

"No; to warn you," Quarles answered. "I have not collected all the details yet, but I think you know more of Miss Farrow than you have admitted, and are inclined to be revengeful. You must not use the weapon which chance has put into your hands."

"Must not?"

"It would be folly. The jewels will be applied for in due course, and there the matter must end. A detrimental word concerning Lady Leconbridge, and your position as sole owner of Bartrams would become awkward, while your chance of getting a footing in the society you are striving so hard to enter would be gone. Unfortunately for you, I know too much. I am inclined to be generous."

"A poor argument," laughed Hartmann. "The interview is over."

"Generosity is at a discount," said Quarles. "By the first post to-morrow Lord Leconbridge must receive from you an ample apology. You must state emphatically that there is not a shadow of truth in the hints you have dropped lately concerning his wife. You must also confess that three years ago you were instrumental in spreading utterly false reports about Helen Farrow. You may excuse yourself as best pleases you."

"I shall send no apology."

"By the first post, please," said Quarles, "or by noon Scotland Yard will be busy with the career of Mr. Jacob Hartmann. Good day to you."

It was not until we were in the empty room at Chelsea, Zena with us, that the professor would discuss the case.

"The difficult way was the right one, Wigan," he said. "You are convinced, I presume, that Hartmann has the diamonds?"

"Yes."

"Let me deal with the banker's part in the story first--some theory in the solution, but with facts to support it. Since Leconbridge is an important member of the Conservative Party, and Hartmann has for some time supported the party, I asked myself why Hartmann had not met Lady Leconbridge before. Lord Leconbridge was practically bound to extend him hospitality; that he had not done so, in the only way serviceable to the banker, pointed to the probability that Lady Leconbridge would not know him. Why? Had he pestered her in her theater days and, because she scorned him, had he been responsible for the gossip three years ago? It was evident, I argued, that there was some connection, in Lord Leconbridge's mind, between Hartmann and the diamonds. The banker had done or said something to make Leconbridge suspicious; had suggested possibly, among other things, that his wife could not produce the diamonds were she asked to do so. The real necklace had come into his hands, and he meant to take his revenge."

"But how did he get the jewels?" asked Zena.

"Let me clear up the banker first," said Quarles. "To-day, Wigan, he gave himself away when he said he would know if Lady Leconbridge were wearing paste. Of course he would know, because he had the real stones. No doubt he would have p.r.o.nounced them paste before the a.s.sembled guests--a disclosure which might have proved disastrous to Lady Leconbridge. Whether Hartmann knows the true story of the necklace or not, I cannot say."