Suli-Karatekin Diamonds: The Hardest Versions of the 1000 Year Unsolved Chess Mystery

This publication presents the Suli-Karatekin Diamonds, a family of forty reverse-ferz shah-and-vizier versus shah-and-vizier shatranj endgame studies related to the historical problem known as Suli’s Diamond. In this reverse-ferz family, the two ferz pieces move on different diagonal complexes and therefore cannot attack or capture one another, which leads to a substantially different winning mechanism from that of the canonical Suli’s Diamond. The study family was first discovered and composed by Tamer Karatekin during research and lesson-preparation work connected to the Shatranj.ai curriculum. The publication documents the family’s relation to the original Suli’s Diamond tradition, presents representative positions and geometrical motifs, and records that the hardest examples in this family require 63 plies to win, compared with 39 plies for the canonical Suli’s Diamond or with 53 plies for Suli's Rough Diamond. One particular position from this group with FEN string, 5k2/8/8/2Q4K/8/8/8/5q2 w, has a diamond shape piece geometry and is named as Suli-Karatekin diamond. The paper also identifies a simpler position and names it as `Suli's Little Diamond` where the solution requires a diamond shape maneuver. A flipped version of this position is also identified with a unique solution and named as `Suli's Flipped Diamond'. This Zenodo record is intended as an archival public release of the study family, its naming, and its core explanatory framework. The PDF serves as the primary descriptive publication for the forty positions and their historical-computational context. Related code, datasets, FEN lists, PGN files, and later revised versions may be linked in subsequent releases.9 April 2026 version over v1 (2 April 2026) added: Updated clearer diagram imagesReference sectionAverbakh's contribution to Suli's Diamond clarified