The opal is said to sharpen the sight of its possessor and cloud the eyes of those who stand about him, so that they can neither see nor mind what is done before them; for this cause it is asserted to be a safe patron of thieves and thefts. Albertus Magnus says, “If you wish to become invisible, take an opal and wrap it in a bay-leaf, and it is of such virtue that it will make the bystanders blind, hence it has been called the patron of thieves.” Nicols gives a glowing description of this stone.[185] “The _opalus_ is a pretious stone which hath in it the bright fiery flame of a carbuncle, the pure refulgent purple of an amethyst, and a whole of the emerauld’s spring glory or virescency, and every one of them shining with an incredible mixture and very much pleasure.” It is reported of Nonius, a Roman senator, that he had rather been deprived of his country and senatorship than part with an opal which he had from Antonius. It is asserted of the cornelian that it causeth him that weareth it to be of a cheerful heart, free from fear and nobly audacious and is a good protection against witchcraft and fascination. “Chalcedony procureth victory to him that is the possessor of it and carrieth it about him. It is much used for signets, for it sealeth freely without any devouring of the wax.”[186] The report on jaspers is that they preserve men from drowning; and “divers do very superstitiously attribute much power and virtue to them if figures, images and characters be engraven upon them. The effects which by this means are wrought in or for any, Andreas Baccius doth attribute to the devil.”[187] We might presume that the ring of Gyges held the opal or the stone known as the Heliotrope or Oriental jasper; for Pliny gives the report of magicians that if this gem be anointed with the juice of the marigold, it will cause him that carrieth it to walk invisible.