"Well, this may or may not be the stone you assert is missing from your stock," said the policeman; "but as long as you can't show that this man took it, I don't see how I can run him in without a regular warrant."
"I think I can throw some light on the matter," said Dick at this point.
All hands looked at him.
"Here's a piece of gum which I saw that man throw into the street after picking something out of it," he said, handing the gum to the manager. "It evidently held the diamond, for it bears a clear impression of a five-carat stone."
"It does, indeed!" said the manager.
"The lady who was in the store looking at rings when you sent me on the errand came up to that man and handed him that piece of gum. It was the singularity of their meeting that aroused my suspicions and caused me to watch and then follow them to this place, particularly after I picked the gum up and saw the impression of a diamond in it. I judged at once that the man must have hidden the stone in the gum and left it somewhere about the counter where the lady found it afterward and brought it to him."
Dick's words seemed to make the matter quite clear to the manager, who was familiar with many of the tricks adopted by diamond thieves to ply their vocation without detection.
"The gum business is an old trick," said the manager. "It's a wonder it did not occur to you," he added, looking at the salesman. "When a thief comes into a store he sometimes carries a piece of adhesive gum like that," he explained to the policeman. "The first thing he does is to attach it to the bottom of the showcase, out of sight. Then he watches his chance, and if he is a sufficiently expert sleight-of-hand artist, he manages at some time during his inspection of the stones to convey a diamond to the gum and force it into it. When the diamond is afterward missed he cheerfully submits to a search, for the stolen stone is not on his person. Later he sends a confederate into the store to get the gum, under cover of an intention to make some kind of a purchase, other than diamonds, at that counter. In this case, it is quite clear to me that the lady was the man's confederate. I think I am fully justified in demanding that fellow's arrest at our risk. It is too bad that the woman got away, but I guess we'll be able to find her. You have her description, Dick," he said to the office boy.
"Yes, sir. I'd recognize her on sight."
"Now, officer, you may arrest that man and take him to the police station. We will go with you and make the charge," said the manager.