The corvette slipped through the darkness of space. Obsidian looked outside the cabin window, and felt like he could see everything. There were stars dotting the black everywhere, and behind it all, a vast, colourful nebula brought depth to it all. It was like staring into a dream.
"It's beautiful, isn't it?" asked a voice behind him.
"Steven? What are you doing here?"
Steven was staring out the window across from him. "I heard you talking about Black Diamond last night, and I wanted to hear more."
"And for that you stowed away here? First of all, the Crystal Gems will be worried sick about you! Second, this is a very perilous mission. We all could die. Did you even think about it before you snuck on board?"
"Yes." Steven had a confident smile on his face. "I want to know everything. Besides, maybe I'll come in handy during the mission."
Obsidian sighed. "Moonstone, could you send a transmission to the Crystal Gems? Tell 'em Steven got on board the corvette."
"Sure thing," said Moonstone from the cockpit.
"Anyway, Steven, what is it you want to know?"
"I want to know about Black Diamond. Why she's kept secret from all but the black gems. What makes her the most powerful diamond."
"Steven, what I'm going to tell you will likely weigh very heavily on you," replied Obsidian. "I think we'd better go sit down."
Obsidian motioned toward a table with two chairs, and they went and sat down.
"So, why is Black Diamond kept secret from most gems, and how is she so powerful?"
"Black Diamond isn't a 'she', Steven. Black Diamond is an 'it'."
"What do you mean, an 'it'?"
"Black Diamond doesn't have a humanoid form. It's a "pure" gem, a gem that has transcended the biological level of other gems."
"So what does Black Diamond look like?"
"Basically, Black Diamond is just…well, a gem. It's an enormous, ancient gemstone, at least the size of this room, that communicates telepathically. It can also see things that haven't happened yet. For all we know, it already knows we're coming."
"When you say ancient, how ancient are you implying?"
"Black Diamond, aside from being the largest gem, is also by far the oldest. It is a remnant of a star that went supernova three billion years ago."
"Three billion years?"
"Yes. A gem only becomes "pure" when it has lived for long enough. In most cases, it must have existed for at least a billion years. Black Diamond has certainly lived for that long."
"Did it ever have a human form?"
"Of course. When first formed, it had the largest humanoid form of any gem, present or past. In human form, it towered above all others, reaching four hundred feet tall. During its early days, it visited sprouting civilizations, nearly all of which regarded it as a god."
"Were there other pure gems?"
"Yes, there were. That is, until the Great Gem War."
