“How did you know?” he muttered.
Again Jimmy was surprised. He had expected 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 jeweller can’t say exactly how he gets on the track of faked stones. He can feel them, he can almost smell them. I worked with a jeweller 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 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 straight away 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 worked. 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 seaside to a bit of white jargoon. Are you satisfied? If it comes to that, I suppose you can hardly be expected to be; convinced is a better word. Are you convinced, or do you hanker after tests like polarised 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 scrutinised Sir Thomas’s pallid face keenly.
“Did you know?” he asked.
He wondered that the possibility had not occurred to him earlier.
“By George, I believe you did!” he cried. “You must have done. So that’s how it happened, is it? I don’t wonder it was a shock when I said I knew about the necklace.”
“Mr. Pitt!”