Mohammedan legend represent the heavens with different stones and gems.
In the middle ages religious ideas become intertwined with astrological and medical practices. Stones do appear in the Bible text throughout. Amethyst is one of the stones mentioned. In Exodus xxviii, 15-30 the Breastplate of judgement had an Amethyst in the third row. God announced victory in battle by means of the twelve stones worn by the high priest on his breast.