"Welcome to Apollo Diamond," Linares says, waving me inside and quickly shutting the door. He hands me a bunny suit, including booties, goggles, and a hair cap, and leads me into a third room. Three men dressed in similar contaminant-control outfits stand around a cylindrical contraption that looks like a heavy-duty coffee urn outfitted with a bolt-on porthole. A preternatural purple-green glow emanates from the window. I peer through the glass. Four diamonds are growing beneath a shimmering green cloud. "It took me a long time to get to this point," says one of the men standing beside the machine....