Dead Guilty

stone. ‘‘This is a moissanite—costs about three hundred dol lars. It has a higher refractive index than a diamond and is almost as hard.’’
‘‘I’ve never heard of a moissanite.’’
‘‘Silicon carbide crystals. It’s named after Henri Moissan, a scientist from Paris. In 1893 he discovered the crystals in a meteorite. Naturally occurring mois sanite is rare, but a way to manufacture it was devel oped in 1995.’’
‘‘Her diamond might have been any one of these.’’
‘‘You have to look at the diamond’s internal struc ture. Think she’ll let you borrow it?’’
‘‘About as much chance as a snowball’s in hell, I imagine. Although, if she thought it could help catch Chris Edwards’ killer, maybe.’’
‘‘Today, a lot of good diamonds are engraved on the girdle—on one of these tiny facets around the girth of the stone—with a serial number and a logo for where it came from. They are also fingerprinted—in a man ner of speaking. The internal structure of each dia mond is unique. People who deal in real diamonds are very concerned about distinguishing their product from the man-made variety.’’
‘‘Tell me, if these nondiamonds are so much cheaper and you have to have a special machine to tell them from the real thing...’’
‘‘Why do people pay so much for diamonds? They are the stones created a billion years ago in the bowels of the earth—the mantle, actually—and were spewed out of the earth by a volcano in molten lava. It’s the mystique, and very clever marketing by the diamond companies.’’
He picked up the diamond. ‘‘Besides, diamonds are cool stones. If the temperature and pressure had been a little less when it was being formed, we’d be writing with this in a pencil.’’
‘‘I do know that graphite is carbon, and that dia monds are formed out of carbon.’’
‘‘Did you know when light passes through a dia mond, it slows down to half its speed?’’
‘‘I would have been more impressed if it speeded up,’’ said Diane.
‘‘You’re a science fiction fan, aren’t you? So am I. Another thing we have in common.’’ Mike began putting the stones back in their marked containers. Instead of putting them back in the drawer, he set them aside in a tray. ‘‘Since they’ve been out of their boxes, I’ll check all of them to make sure I didn’t mix them up.’’ He took them back to the storage room.
‘‘I didn’t know we have such valuable gemstones,’’ said Diane, when he returned.
‘‘Kendel’s been helping to increase our number of reference gems. I tell you, if I’m ever on a scavenger hunt where my life depends on the outcome, I want that woman on my team.’’
Diane nodded and smiled. ‘‘I’ve been very pleased with her. Did she acquire the diamond we just looked at?’’
Mike nodded. ‘‘She got it out of Mrs. Van Ross. We decided to keep it in the reference collection rather than exchange it with the one on display in the rock room. The one on display is a larger diamond but not near the quality, but with the lighting it’s a little more impressive because of its size.’’
‘‘It’s on a black background, isn’t it?’’
Mike grinned. ‘‘Yep.’’
‘‘Mike, I appreciate the lesson in diamonds.’’ She stood up to go.
‘‘Have you eaten?’’
‘‘Mike...’’
‘‘Come on, Doc. You have to eat. We could eat in the museum restaurant. We’d just have to walk downstairs.’’
Diane thought for a second. ‘‘Oh, all right. I am hungry.’’
‘‘Great! Besides, I have something I need to ask you.’’
    Between the sets of huge double doors at the en trance to each wing of the museum, Diane had added a new door that led down a long hallway to the restau rant that remained open after the museum closed. She and Mike took one of the elevators across from the rock room down to the first floor. It let them out at the midpoint of the hallway.
    Photographs of pieces from the museum hung along the long walls—the inside spiral from a chambered nautilus, starfish, sea horses, seashells, rocks, minerals and gemstones, dinosaurs, wolves, butterflies, birds and flowers. A preview of what the museum offered. Diane had framed several copies for her apartment. There was nothing as peaceful and soothing to her as a seashell.
    Several couples were walking down the hallway to the restaurant when Diane and Mike emerged from the elevator.
    ‘‘Oh, the museum is still open. Let’s go look at the