The Kingman mine in northwestern Arizona was one of the largest turquoise mines in North America. The term high blue refer to the blue color usually displayed in this stone. The mine became famous for its rounded, bright blue nuggets with black matrix. Few turquoise mines produced nuggets, especially of this quality. The Colbaugh's own this mine and the Turquoise Mountain mine. They have recently gone back into the section of the Kingman mine and are digging and bringing our some new Natural Kingman Turquoise.