In medieval Bohemia the knowledge of precious stones and their employment for curative purposes is well attested.
There exists a Bohemian manuscript list of precious stones dated in 1391, in which no less than 55 different gems are noted.
Their medicinal use in Bohemia at this time is vouched for by the Synonima Apothecariorum where precious stones are listed among the materials of the apothecaries art.
In the testaments of royal and princely personages, medical stones are often bestowed as precious legacies.
Thus in the will of the Hessian prince, Henry VIII of Furstenberg, the following stones are mentioned as especially costly objects: a « crabstone » (Krebstein), a bloodstone, and a gravel-stone, the latter being a piece of jade or nephrite.
The crabstone, sometimes called crab’s-eye, is a chalky concretion which forms on either side of the stomach of a crab or other crustacean during the moulting period, and this was and is still used as an eye-stone for the removing of foreign bodies that have entered the eye, the eye-stone being introduced under the eyelid.
This results in a rapid flow from the tear-ducts which often washes away the foreign bodies, the passage of the stone across the eyeball occasionally aiding in the work by rubbing off the body.
