It is very simple.

In that half hour, some one, somehow, abstracted them.
Certainly it was not you.

You see how little I ask--and I pay well, do I not?
And so I gave you until to-night.

Three days have gone, and I have said nothing, and the body has not been found--eh?
But to-night--eh--it was understood! The rubies--or the chair." Burton's lips moved, but it was a moment before he could speak.
"You wouldn't dare!" he whispered thickly.

"You wouldn't dare! I'd tell the story of--of what you tried to make me do, and they'd send you up for it." Old Isaac shrugged with pitying contempt.
"Is it, after all, a fool I am dealing with!" he sneered.