Mourning jewelry has been around since at least the 16th century, but it is widely associated with the Victorian Era, when mass production made it affordable. The trend reached its high point after the death of Prince Albert in 1861, when Queen Victoria, as well as members of her court, wore black clothing and matching mourning jewelry for decades.

Thanks to this royal example, black jewelry became quite fashionable. The best pieces were made out of jet, a fossilized coal found near Whitby, England. Less-expensive alternatives included black glass, black enamel, vulcanite (a hardened rubber,) and bog oak, which is more of a brown color but still dark enough to express somber sentiments.

Some of the most interesting examples of mourning jewelry included hairwork, which describes bracelets, necklaces, and rings made from woven human hair. The hair was not necessarily from the deceased—in the middle of the 19th century, 50 tons of human hair a year was imported into England for use by the country’s jewelers. To create a connection to a deceased loved one, their initials were often discreetly woven into the object...