“A diamond, sir? A precious stone. It cuts into glass as though it were putty.” “It’s more than a precious stone. It is the precious stone.” “Not the Countess of Morcar’s blue carbuncle!” I ejaculated. “Precisely so. I ought to know its size and shape, seeing that I have read the advertisement about it in The Times every day lately. It is absolutely unique, and its value can only be conjectured, but the reward offered of £1000 is certainly not within a twentieth part of the market price.” “A thousand pounds! Great Lord of mercy!” The commissionaire plumped down into a chair and stared from one to the other of us. “That is the reward, and I have reason to know that there are sentimental considerations in the background which would induce the Countess to part with half her fortune if sh