CAIS and Scale AI release HLE-Diamond, a refined 1,000-question subset of Humanity's Last Exam

On September 22, 2026, the Center for AI Safety and Scale AI released HLE-Diamond, which the release notes describe as a refined subset of the Humanity's Last Exam (HLE) question collection, produced through a year-long process of cleaning and refinement with input from research communities. HLE-Diamond has 1,000 questions, split evenly into 500 reasoning and 500 knowledge questions, and is designed to be answered closed-book, with separate recommended settings for evaluations that use tools. The dataset is on Hugging Face as cais/hle-diamond, where the card lists an MIT license, requires agreeing to share contact information before access, and asks that the dataset not be publicly shared or re-uploaded.123

USASI. (2026, October 13). CAIS and Scale AI release HLE-Diamond, a refined 1,000-question subset of Humanity's Last Exam. United States of America Superintelligence. https://unitedstatesofamericasuperintelligence.com/news/cais-and-scale-ai-release-hle-diamond/

@misc{usasi_news_cais_and_scale_ai_release_hle_diamond,
  author = {{USASI}},
  title = {CAIS and Scale AI release HLE-Diamond, a refined 1,000-question subset of Humanity's Last Exam},
  year = {2026},
  month = oct,
  howpublished = {\url{https://unitedstatesofamericasuperintelligence.com/news/cais-and-scale-ai-release-hle-diamond/}},
  note = {United States of America Superintelligence. Last updated 2026-10-13}
}