He held the two side-by-side and compared them. The facets on both were remarkably similar, although the blue one was transparent, while the lamp-crystal was an opaque white, like the quartz crystals that people used to wear as necklaces. Well, the only way to find out is to try it. He set the blue crystal in the lamp and was about to push the button on the base when the nurse shouted at him and batted the lamp away from his hand, sending the crystal tumbling across the floor.