Sodalite is a blue gemstone almost invariably veined with white streaks or markings. Its ideal colour is an intense blue, and it comes in all shades of blue from light blue to deep royal-blue, and from grayish-blue to violet. Different shades of blue will often be present in a single gemstone. Sodalite is an opaque gemstone, though it is slightly translucent on thin edges. Sodalite gets its name from its sodium content. It has a hardness of 5.5 to 6 on the Mohs scale.