Lapis lazuli is an opaque to translucent blue, violet-blue, or greenish-blue semi precious gemstone composed mainly of lazurite and calcite. It is often dyed to deepen and improve its color and contains the minerals calcite (which decreases its value), pyrite (which can increase its value), and sodalite. The rich blue color is due to the sulfur inherent in the structure of lazurite. Lazurite is resistant to atmospheric gases, is lightfast and possesses good hiding power. It is durable with all other permanent pigments.
