On the subject of brooches you can find this little gem in Elizabeth Gaskell's Cranford:
The expenditure in dress in Cranford was principally in that one article referred to [i.e. the cap]. If the heads were bured in smart new caps, the ladies were like ostriches, and cared not what became of their bodies. Old gowns, white and venerable collars, any number of brooches, up and down and everywhere (some with dogs' eyes painted in them; some that were like small picture-frames with mausoleums and weeping-willows neatly executed in hair inside; some, again, with miniatures of ladies and gentlemen sweetly smiling out of a nest of stiff muslin) - old brooches for permanent ornament, and new caps to suit the fashion of the day; the ladies of Cranford always dressed with chaste elegance and propriety, as Miss Barker once prettily expressed it.Brooches were very popular throughout the nineteenth century, and this passage nicely satirises some of the fashions of the day.
As the ladies of Cranford are all either widows or spinsters, it comes as no surprise that they should wear mourning jewellery: mausoleums and weeping-willows are some of the neoclassical symbols of death, which became popular in the late eighteenth century. To top the mourning symbolism, here the pictures are executed in hair, namely the hair of the person who passed away and is commemorated with this piece of jewellery. Normally, hair jewellery was a bit less intricate: a lock of hair was simply placed inside a locket, or the hair was plaited. This was done either by professional hair-artists or by amateurs. Here's a beautiful example for a hair brooch from the collection of the V&A Museum.
Yet not all hair jewellery was for mourning; it was also used for love tokens or as gifts of friendship. This is also true for another kind of brooch mentioned by Gaskell, miniature portraits. A cheaper alternative to a painted portrait was the black-paper silhouette, set behind glass, which gained in popularity from the late eighteenth century onward. The most mysterious form of portrait jewellery, however, are eye miniatures: as only the eye of the person portrayed was shown, his or her identity was kept secret.
Now one of the most striking characteristics of the fictitious town of Cranford is that there are no men--hence the ladies of Cranford don't wear brooches showing the eye of a beloved person. Instead, their eye portraits feature their beloved doggies. Yet this is not just a satirical exaggeration on Gaskell's part: in the collections of the V&A Museum there is a Victorian brooch with the portrait of a Yorkshire terrier.
The true eccentric however, would have probably chosen a piece of mouse jewellery, which was sold by Messrs Thornhill & Co. of New Bond Street. "However disagreeable a live mouse may be running about one's room," one of their ads reads, "in itself it is a gracefully shaped little animal, which may well form part of an eccentric ornament, especially if skilfully modeled and arranged. Whether the substitution of little pigs in the place of mice, which Messrs Thornhill likewise intend to introduce, and which are now the fashion in Paris, will turn out equally satisfactory from an artistic point of view, remains to be seen."
Oh, the lucky heroine who gets to wear a piggy brooch!