"But you don't quite see my plan yet.

You have not altogether grasped it.

Allow me to explain it to you." His son lay back upon the sofa with a look of resignation upon his face.
Girdlestone continued to stand upon the hearth-rug and spoke very slowly and deliberately, as though giving vent to thoughts which had been long and carefully considered.
"You see, Ezra," he said, "diamonds, being a commodity of great value, of which there is never very much in the market at one time, are extremely sensitive to all sorts of influences.

The value of them varies greatly from time to time.

A very little thing serves to depreciate their price, and an equally small thing will send it up again." Ezra Girdlestone grunted to show that he followed his father's remarks.
"I did some business in diamonds myself when I was a younger man, and so I had an opportunity of observing their fluctuations in the market.
Now, there is one thing which invariably depreciates the price of diamonds.