What is the State Gemstone of California?

The State Gemstone of California is the Blue Diamond. This designation reflects California's significant production of various gemstones, but the blue diamond stands out due to its exceptional color and rarity. Blue diamonds are particularly noted for their stunning hue, which is caused by the presence of boron during their formation. This state symbol emphasizes both the geological richness of California and its position in the gemstone trade, showcasing a unique and valuable natural resource within the state.

The other gemstones mentioned, such as ruby, emerald, and amethyst, while valuable and popular in their own right, do not hold the same official status as the blue diamond in California’s state symbols. Each of these stones has its own geographical associations and significance, but they do not represent California as the blue diamond does, making the latter the correct choice for the state's official gemstone.