The same suspicion had evidently been in the mind of the expert, for he had been carefully examining the four stones with the aid of a lens. He now submitted them to several tests, and finally turned cheerfully to Mortimer.
"I congratulate you, sir," said he, heartily. "I will pledge my reputation that all four of these stones are genuine, and of a most unusual degree of purity."
The colour began to come back to my poor friend's frightened face, and he drew a long breath of relief.
"Thank God!" he cried. "Then what in the world did the thief want?"
"Probably he meant to take the stones, but was interrupted."
"In that case one would expect him to take them out one at a time, but the setting of each of these has been loosened, and yet the stones are all here."
"It is certainly most extraordinary," said the inspector. "I never remember a case like it. Let us see the watchman."
The commissionaire was called—a soldierly, honest-faced man, who seemed as concerned as Ward Mortimer at the incident.
"No, sir, I never heard a sound," he answered, in reply to the questions of the inspector. "I made my rounds four times, as usual, but I saw nothing suspicious. I've been in my position ten years, but nothing of the kind has ever occurred before."
"No thief could have come through the windows?"