“It’s the most perfect blue-white I’ve ever seen,” the expert announced at last.  “I dare say it’s the most perfect in the world.”

Mr. Latham arose suddenly and strode over to Mr. Czenki, who was twisting the jewel in his fingers, singling out, dissecting, studying the colorful flashes, measuring the facets with practised eyes, weighing it on his finger-tips, seeking a possible flaw.

“The cutting is very fine,” the expert went on.  “Of course I would have to use instruments to tell me if it is mathematically correct; and the weight, I imagine, is—­is about six carats, perhaps a fraction more.”

“What’s it worth?” asked Mr. Latham.  “Approximately, I mean?”

“We know the color is perfect,” explained Mr. Czenki precisely.  “If, in addition, the cutting is perfect, and the depth is right, and the weight is six carats or a fraction more, it’s worth—­in other words, if that is the most perfect specimen in existence, as it seems to be, it’s worth whatever you might choose to demand for it—­twenty, twenty-five, thirty thousand dollars.  With this color, and assuming it to be six carats, even if badly cut, it would be worth ten or twelve thousand.”

Mr. Latham mopped his brow.  And this had come by mail, unregistered!

“It would not be possible to say where—­where such a stone came from—­what country?” Mr. Latham inquired curiously.  “What’s your opinion?”

The expert shook his head.  “If I had to guess I should say Brazil, of course,” he replied; “but that would be merely because the most perfect blue-white diamonds come from Brazil.  They are found all over the world—­in Africa, Russia, India, China, even in the United States.  The simple fact that this color is perfect makes conjecture useless.”

Mr. Latham lapsed into silence, and for a time paced back and forth across his office; Mr. Czenki stood waiting.

“Please get the exact weight,” Mr. Latham requested abruptly.  “Also test the cutting.  It came into my possession in rather an—­an unusual manner, and I’m curious.”

The expert went out.  An hour later he returned and placed the white, glazed box on the desk before Mr. Latham.

“The weight is six and three-sixteenths carats,” he stated.  “The depth is absolutely perfect according to the diameter of the girdle.  The bezel facets are mathematically correct to the minutest fraction—­thirty-three, including the table.  The facets on the collet side are equally exact—­twenty-five, including the collet, or fifty-eight facets in all.  As I said, the color is flawless.  In other words,” he continued without hesitation, “I should say, speaking as an expert, that it is the most perfect diamond existing in the world to-day.”

Mr. Latham had been staring at him mutely, and he still sat silent for an instant after Mr. Czenki had finished.

“And its value?” he asked at last.