Modern, traditional, and zodiac birthstones for every month of the year, with editorial framing on where Zultanite (color-change diaspore) fits relative to each official list. Twelve dedicated entries — January through December — covering both the canonical birthstone choices and the visual and mineralogical relationship between Zultanite and the official picks. Note: Zultanite was discovered too late (commercial production since the early 2000s) to enter any historical list.