Hair bands (rings with hair woven through a compartment in the shank) became popular from the 1870s. Pieces in this form can be seen dating back to the 1790s, but from this time, their popularity grew immensely. The mourning industry was on the decline from the mid 1800s, but these pieces can be seen right up to the first quarter of the 20th Century.
This particular piece from 1876 shows a heavier style that would be adopted later in the 1880s-90s and become one of the most consistent and popular mourning and sentimental bands available. It shows the woven hairwork through the grooves in the ring (which has been treated to prevent environmental damage) and the shield on top. You can estimate the year of the ring (if not inscribed) by its construction and weight. Generally, the later the ring, the lighter it becomes, as alloy construction and mass production of the bands provided a relatively cheap love token to be given as a sentimental gift. These particular bands could also be ordered from jewellery catalogues from the 1870s onwards.
As much of the hairwork was often not the original donor’s hair, it would not be obtuse to suggest that many were produced then colour-matched to the given hair. For mourning purposes, given their relatively inexpensive nature, they were given out at funerals to friends and family for souvenirs of the deceased, which was now permeating class-rank, rather than reserved for the higher classes of society. This leads to the necessity of mourning as a social function, something helped along by its infusion into mainstream fashion and the rise of the mourning industry. For more on this, see the following articles: