In Vernor Vinge's A Deepness in the Sky, the OnOff system is featureless save for the spider planet, and some asteroid-sized diamonds. Is the origin of the diamonds ever explained or hinted at?

I haven't read the book in years and my copy is in storage, but I have a vague recollection of thinking that the OnOff star was a form of transport for Powers who wanted to explore the Unthinking Depths, creating its own local bubble of Transcend when activated. The diamonds therefore could be the dormant, hibernating husks of the Powers themselves, reduced to ordinary diamond when in lower zones, but activated when the time comes.

  • Been a long time since I read it, but I seem to recall a character saying they expected to find the diamonds.
    – Zeiss Ikon
    Commented Jul 8, 2022 at 11:01
  • 1
    I think they are not explained within "Deepness...": "They were just another mystery of the OnOff system." I don't know if Vinge gave more details in another of the Zones of Thought works. Commented Jul 8, 2022 at 13:18

1 Answer 1


There are several theories mooted in the novels, but nothing conclusive. One school of thought is that they're remnants of planetary collisions and ordinary physical processes.

But even the Qeng Ho had been a little intimidated by these boulders. Asteroids like this didn’t exist outside of theory. And although these rocks weren’t single gems, there was a vast, crystalline order to them. The cores of gas giants, planets blown away in some long-ago detonation? They were just another mystery of the OnOff system.

A Deepness in the Sky

Later on there's a hint of a suggestion that they might be artifacts left by an elder civilisation.

“Yes. It makes the conclusion all the more fantastic. For forty years we’ve thought the diamond powders of Arachna were either infalls or biological skeletons. Now it looks like they are fossil processing devices. And at least some of them reassert their mission when brought close together. Like localizers, but much much smaller, and with a special purpose…to manipulate physical laws in ways we don’t begin to understand.”

Trinli looked as if someone had punched him in the face, as if decades of bombast had been beaten out of him. He said softly, “Nanotech. The dream.”

“What? Yes, the Failed Dream. Till now.” The Podmaster looked up at the tile lying on the ceiling. He smiled. “Whoever visited here, it was millions or billions of years ago. I doubt we’ll ever find any camp tents or garbage middens…but the signs of their technology are everywhere.”

Vinh: “We were looking for starfarers, but we were too small and all we saw were their ankles.” He tore his gaze down from the ceiling. “Maybe even these—” He waved at the window, and Gonle realized that he was talking about the big diamonds of L1. “Maybe even these are artifacts.”

Brughel moved forward in his chair. “Nonsense. They are simple diamond rocks.” But there was an edge of uncertainty in the aggressive look he flashed around the table.

  • Should your first quote be attributed to A Deepness in the Sky?
    – jl6
    Commented Jul 22, 2022 at 8:08
  • @jl6 - ah yes. You're not wrong.
    – Valorum
    Commented Jul 22, 2022 at 8:12

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