From Death Made Material: The Hair Jewelry of the Brontës:
If the Brontës’ things feel haunted in some way, like Emily’s desk and its contents, then the amethyst bracelet made from the entwined hair of Emily and Anne is positively ghost-ridden. Over time the colors have faded, the strands grown stiff and brittle. Charlotte may have asked Emily and Anne for the locks as a gesture of sisterly affection. Or, the tresses were cut from one or both of their corpses, an ordinary step in preparing the dead for burial in an era when mourning jewelry with hair became part of the grieving process. Charlotte must have either mailed the hair to a jeweler or “hairworker” (a title for makers of hair jewelry) or brought it to her in person. Then she probably wore it, carrying on her body a physical link to her sisters, continuing to touch them wherever they were...Much more at the very interesting Longreads source.
Part of the body yet easy to separate from it, hair retained its luster long after the rest of the person decayed. Portable, with a shine like certain gems or metals, hair moved easily from being an ornamental feature of the body to being an ornament worn by others. By the 1840s, hair jewelry had become so fashionable that advertisements for hair artisans, designers, and hairworkers ran in newspapers, and magazines printed a sea of articles on the minute particulars of the fad. The London jeweler Antoni Forrer, a well-known professional hairworker in the 1840s, had fifty workers fully employed at his Regent Street store. At the Great Exhibition, around eleven displays of the art garnered glowing reviews, including pictures embroidered in hair of Queen Victoria, the Prince of Wales, and the Hamburgh Exchange. A tall vase “composed entirely of human hair” and a “horn filled with artificial flowers in human hair, representing the horn of plenty,” were other impressive exhibits. Hairwork kept women’s hands busy at home, another one of those many domestic arts, like needlework, quilling, shellwork, and taxidermy. Fashion magazines discussed the homecraft of hairworking and included jewelry patterns, instructions, and tips. Hair wreaths, set into shadow boxes or under glass domes, also had their day, as did the use of hair in drawing and painting. One industrious woman copied a Rembrandt using only hair in a cross-stitch. Charlotte brought the device of a “cambric handkerchief with a coronet wrought upon it in black hair” into more than one early story, a means of signaling that the male owner has a secret lover who embroidered it with her own hair.
The hairwork process—involving boiling the hair to clean it, then weaving it on specially designed round tables (which could be mail ordered) with a series of weights that were attached to the strands of hair—was described in instructional manuals, such as Mark Campbell’s popular 1865 Self-Instructor in the Art of Hair Work. The tight weave of the bracelet with Anne’s and Emily’s hair, pictured at the start of this chapter, was likely achieved this way, although in this case probably by a professional, who then attached the ends of the hair to the metal. A bracelet made of Anne’s hair, from locks given to Ellen Nussey by Charlotte after Anne’s death, has a slightly different weave, and Ellen may have made it herself. By the time Ellen died, she had at least three hair bracelets, four hair brooches, a hair ring, and a couple of loose locks, much of it hair from the Brontë family.