The choice of stone for the magical gems was not random, but played an essential role for their context of representation and use, i.e. for the effect to be achieved or hoped for.
Thus the physician Galenos of Pergamon (129-216 AD) goes so far as to say (Gal., de simpl. Med. 9, 2.19; t. XII p. 207 ed. Kühn) that the material was even more important for the effectiveness than the motif carved into the stone, for he had cured his own stomach problem with a green jasper even without the chnoubis representation usually used for these ailments. The lion-headed and serpentine Chnoubis was considered the "Lord of the Stomach". (AVS)
Former August Kestner Collection, Rome
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