“Have you anything else?” No robot now. Rainwater sounded genuinely interested.

I lay the five-by-seven on his desk.

The old man’s shoulders twitched, and I heard a sharp intake of air.

Rainwater switched back to the bifocals. Stared some more at the photo. Finally, his eyes met mine.

“My nephew put you up to some kind of stunt?”

“No, sir.”

“Sweet Lord in the rushes.”

Chapter 36

“DID YOU COLLECT THIS?”

“No, sir.”

“Who did you say you are?”

I repeated my name but offered nothing else.

“Got any idea what diamond indicator minerals are?”

“Crystals that form in the earth’s upper mantle as companions to diamonds.”

“Hm.”

“The difference is, DIMs are millions of times more numerous, so they’re worth next to nothing.” Trying to impress.

Rainwater hit a keyboard combo to save his work. “Do you know how to look through a scope, young lady?”

“I do.” Wishing Binny could have heard the appellation.

The old man swiveled and pulled the cover from a microscope I hadn’t noticed in the jumble behind his desk. The thing was primitive, probably from a student lab. “Prefer a scanning electron microscope, but this old gal will do.”

Rainwater transferred my sample to the viewing plate. Then he flicked a switch, shoved his glasses onto his forehead, peered through the eyepieces, and adjusted focus.

“Look at this.” Rolling his chair sideways.

I squeezed behind the desk and bent down.

And was amazed at the beauty of what I saw.

“That’s magnified two hundred times.”

“Wow,” I said.

“Pretty, eh? When a prospector is out panning or bagging or however he does his sampling, he’s mostly looking for hue.”

I was mesmerized by the colors and shapes of the crystals.

“See the red and orange ones? Those are from the garnet group. The green to sort of lemony-yellow ones are from the pyroxene group. Olivine is one. The black guys are ilmenites.”

“What causes the color differences?”

“Iron, manganese, and chromium content.”

“So you’re saying this sample contains diamond indicators.”

“It’s loaded. One of the richest I’ve ever seen. See those big green ones?”

“Yes.”

“And this.”

I straightened. Rainwater was holding the five-by-seven of the gravel in Ruben’s velvet sack.

“Good call including a scale.” He pointed at the green pebbles. “These are chunks of chrome diopside. Usually, they’re microscopic. The biggest I can recall seeing was maybe one centimeter. These are almost two centimeters each. Hell, you could mount these babies and sell them in a jewelry store.”

“Chrome diopside?” Calm.

“Crystals that form deep within the earth, then get carried to the surface in a rock called kimberlite, which is softer. Over the eons the kimberlite erodes away, leaving the crystals intact.”

“So this came from a site near a kimberlite pipe?” Calm.