That is the value of the chance."

"But," exclaimed Ricardo, "those pearls were of great value, and I have heard at a trial expert evidence given by pearl merchants. All agree that the pearls of great value are known; so, when they come upon the market----"

"That is true," Hanaud interrupted imperturbably. "But how are they known?"

"By their weight," said Mr. Ricardo.

"Exactly," replied Hanaud. "But did you not also hear at this trial of yours that pearls can be peeled like an onion? No? It is true. Remove a skin, two skins, the weight is altered, the pearl is a trifle smaller. It has lost a little of its value, yes--but you can no longer identify it as the so-and-so pearl which belonged to this or that sultan, was stolen by the vizier, bought by Messrs. Lustre and Steinopolis, of Hatton Garden, and subsequently sold to the wealthy Mrs. Blumenstein. No, your pearl has vanished altogether. There is a new pearl which can be traded." He looked at Ricardo. "Who shall say that those pearls are not already in one of the queer little back streets of Amsterdam, undergoing their transformation?"

Mr. Ricardo was not persuaded because he would not be. "I have some experience in these matters," he said loftily to Hanaud. "I am sure that we shall lay our hands upon the criminals. We have never failed."