Of a similar white radiance is the stone that is known as "astrion,"[1] closely resembling crystal in its nature, and found in India and upon the coasts of Pallene.[2] In the centre of it there shines internally a brilliant star, with a refulgence like that of the moon when full. Some will have it that this stone receives its name from the fact that, when held opposite to the stars, it absorbs the light they emit and then returns it. The finest stones, they say, are those of Carmania, there being none more entirely free from all defects. They add, also, that a stone of inferior quality is known as "ceraunia,"[3] and that, in the worst of all, the light is very similar to that given by a lamp.