xpected indignant denials and
demands for proof, excited reiteration of the statement that the
stones had cost twenty thousand pounds.

"How did I know?" he repeated. "If you mean what first made me
suspect, I couldn't tell you. It might have been one of a score of
things. A jeweler can't say exactly how he gets on the track of fake
stones. He can feel them. He can almost smell them. I worked with a
jeweler once. That's how I got my knowledge of jewels. But, if you
mean, can I prove what I say about this necklace, that's easy.
There's no deception. It's simple. See here. These stones are
supposed to be diamonds. Well, the diamond is the hardest stone in
existence. Nothing will scratch it. Now, I've got a little ruby, out
of a college pin, which I know is genuine. By rights, then, that
ruby ought not to have scratched these stones. You follow that? But
it did. It scratched two of them, the only two I tried. If you like,
I can continue the experiment. But there's no need. I can tell you
right now what these stones are, I said they were paste, but that
wasn't quite accurate. They're a stuff called white jargoon. It's a
stuff that's very easily faked. You work it with the flame of a
blow-pipe. You don't want a full description, I suppose? Anyway,
what happens is that the blow-pipe sets it up like a tonic. Gives it
increased specific gravity and a healthy complexion and all sorts of
great things of that kind. Two minutes in the flame of a blow-pipe
is like a week at the seashore to a bit of white jargoon. Are you
satisfied? If it comes to that, I guess you can hardly be expected
to be. Convinced is a better word. Are you convinced, or do you
hanker after tests like polarized light and refracting liquids?"

Sir Thomas had staggered to a chair.

"So, that was how you knew!" he said.

"That was--" began Jimmy, when a sudden suspicion flashed across his
mind. He scrutinized Sir Thomas' pallid face keenly.

"Did you know?" he asked.

He wondered that the possibility had not occurred to him earlier.
This would account for much that had puzzled him in the other's
reception of the news. He had supposed, vaguely, without troubling
to go far into the probabilities of such a thing, that the necklace
which Spike had brought to him had been substituted for the genuine
diamonds by a thief. Such things happened frequently, he knew. But,
remembering what Molly had told him of the care which Sir Thomas
took of this particular necklac