The greater part of the splendid precious stones in the collection of the English banker Henry Philip Hope were set in rings. One of the finest and most interesting of these gems was the beautiful sapphire often called “Le Saphire Merveilleux,” the title of a story written by Mme. de Genlis, who had seen the stone when it formed part of the collection of the Duke of Orleans. Its peculiar charm is that its color changes when seen by artificial light. In daylight it is a beautiful sapphire blue, but by candle light, or other yellow light it acquires an amethystine hue.[538] This fine sapphire, interesting both for its rare dichroism and its historic associations, was sold about 1898 for £700 ($3500). It weighs 19⅛ metric carats. Another attractive gem in the Hope Collection is a cabochon-cut amethyst, engraved in intaglio with the figure of a Bacchante carrying a thyrsus. At the back of the stone are two strata of different colors, one a whitish gray, the other showing brown spots on a velvet ground. This peculiarity has been skilfully utilized by the engraver, who has cut on the stone the form of a panther in relief.[539] The so-called “Pennsylvania Dutch,” largely Germans from the southern parts of Germany, made, in the early days, rings out of horseshoe nails.[540] The good-luck supposed to be inherent in the horseshoe was probably believed to extend to the detachable nails also, so that these rings might have been looked upon as endowed with magic or talismanic virtue. Lord Bacon (1561–1626) in his “Sylva Sylvarum,” published in 1626, suggests a curious test of telepathy. This is that two parties to an agreement or contract, should exchange rings, each wearing the other’s ring, and they are then to note whether, in case the contract or promise should be broken by one of the parties, the other would become sensible of this by means of an influence transmitted through the ring. He adds that it has been regarded as a help to the continuance of love to wear a ring or a bracelet of the loved one, but he believes that “this may proceed from exciting the magnetism, which, perhaps, a glove, or other like favour, might do as well.”