Zone of ai-claimed and settled worlds some 10-20 ly from Sol.
After being expelled from the Solar System in the Interplanetary Age, many ahuman and solipsistAI entities colonised nearby systems and built themselves virtopias. Most of these systems were red dwarf stars, but the brighter stars Altair and Procyon were also claimed. The Diamond Belt got its name from the observed fact that most of these entities used diamond-based computronium for data processing.
In many cases they were total isolationists, hogging resources but not doing anything. The Diamond Belt AIs formed an interesting political group in the Inner Sphere; sometimes actively hostile, sometimes simply non-communicative, occasionally bizarre. For the most part these systems were considered no-go areas for human colonisation efforts.
The Diamond Belters generally operated independently of each other, and many sent out waves of secondary colonisation which became the Diamond Network and the Solipsist Panvirtuality. Today most former Diamond Belt systems have joined one or another of these two metaempires; some, on the other hand, have become integrated with the human-friendly Sephirotics.