The Types segmentation differentiates the market by crystal composition, geometry, and purity level, each factor influencing cost structure and performance envelope. Doped CsI (typically thallium‑ or sodium‑doped) enhances light output and decay time, making it the preferred choice for high‑throughput imaging and fast‑timing detector systems; its premium price captures a sizable portion of revenue despite lower volume. Undoped CsI, valued for its intrinsic radiation hardness, is favored in high‑energy physics where long‑term stability outweighs maximum light yield, contributing a niche but high‑margin segment. Size classifications—small (≤1 cm), medium (1‑5 cm), and large (>5 cm)—align with device form‑factor requirements; large crystals dominate the medical imaging market, while smaller formats serve portable security devices. Purity grades, ranging from standard to ultra‑high purity, affect defect density and thus scintillation uniformity; ultra‑high‑purity crystals command the highest price points, especially in research applications. This typology underpins the High Performance Cesium Iodide Crystals segmentation framework, clarifying how product differentiation drives overall market valuation.