In the twelfth century, Marbodius the Bishop of Rennes lavished praises upon the sapphire. It is quite natural that he should lay especial stress upon the use of the sapphire for the adornment of rings, for it was in his time that sapphire was beginning to be regarded as the stone most appropriate for ecclesiastical rings. The sapphire was like the pure sky, and mighty Nature had endowed it with so great a power that it might be called sacred and the gem of gems.

Sapphire: Also Wytches Love Well This Stone

Fraud was banished from its presence and necromancers honored it more than any other stone, for it enabled them to hear and to understand the obscure oracles. The traditional virtue of the sapphire as an antidote against poison is noted by Bartolomaeus Anglicus, who claims to have seen a test of its power. Voicing the general belief that the sapphire was endowed with power to influence spirits, Bartolomaeus says:

AIso wytches love well this stone,

for they wene that they may

werke certen wondres by vertne of this stone.