CHAP. 47.—ASTERIA.
Next among the white stones is "asteria," [Note] a gem which
holds its high rank on account of a certain peculiarity in its
nature, it having a light enclosed within, in the pupil of an
eye as it were. This light, which has all the appearance of
moving within the stone, it transmits according to the angle of
inclination at which it is held; now in one direction, and
now in another. When held facing the sun, it emits white
rays like those of a star, and to this, in fact, it owes its name. [Note]
The stones of India are very difficult to engrave, those of Carmania being preferred.