These gems always come in sets of at least two polished quarts spheres approximately 3 cm. in diameter. In rare cases, they have been found in sets of 3, 4, or even 5.
By holding one of the gems in front of the user and looking down upon it, a small colored (usually blue) dot or dots appear(s) in the sphere. The location of the dot(s) within the sphere indicate the direction and relative distance of the other sphere(s). The further the other sphere is away from this one, the closer to the edge of the sphere the dot appears. Relative altitude can be estimated by holding the sphere up and in front of the user's face to look at the gem from the side. The range at which these gems will function is 1,000 km.
It is better to idealize the realistic than to realize the ideal.