On June 28, 1973, the General Assembly designated the emerald as the state’s official precious stone.Emeralds are a variety of the mineral beryl. Beryl is colorless in its pure state, but chromium turns beryl green. The aquamarine is blue beryl, and there are also yellow, light green, red and pink varieties. Beryl, in all its variety of colors, is found among mica, quartz and feldspar, all of which are abundant in the North Carolina mountains.